[Pulsar]

Morning,

I think it is about time to start documenting the loft conversion I've been planning in my head for nearly 2 years. I took the first tentative steps over the Easter weekend, gutting the room ready for the initial build stages. I'm creating this thread because I want to share my experiences with you guys, hopefully helping others who may attempt something similar in the future and to ask for advice and opinions on the choices I make. Here's a little background.

I bought the house I live in now in July 2007. It is a 3 bed 1930's semi-detatched, a world away from our first house (a 2 bed, new build end terrace) which came to us in quite a state. Since moving in we've been hard at the DIY to bring the main living areas 'up to spec'. So far we've replaced the kitchen and bathroom, totally ripped out the lounge and decorated the dining room. Every room in the house needs re-plastering as the original stuff is being held on by the wallpaper!

My wife fell in love with the house on first sight, and although we viewed loads of properties she was never swayed from it. I was less convinced as I had a better understanding of the work involved in renovating such a property, but the one thing that kept bringing me back was the loft! The previous owner had done a part loft conversion (a very small part) by cross battening the ceiling timbers and laying a chipboard floor, erecting studding to make some false walls and a ceiling and added a flight of stairs from the third bedroom to the loft.

None of the work was carried out to building regs and the loft wasn't sold as another bedroom, simply an accessible storage room. The insulation up there was very poor, the third bedroom was basically the same temperature as outside (not great in the winter) and made it unusable. My plan for the loft space was always to make it my ultimate dedicated room (I've had 2 before, but they weren't amazing by any stretch of the imagination) and now I'm finally in a position to realise this dream.

I'm lucky that the loft is quite generous with good ceiling height and full gable walls. There is only 1 structural timber that needs to be removed, but I've already taken advice on this and shall document it in later posts.

I've been messing with Google sketchup for a few months to get an idea of what I'm going to do with the space. I feel that I'm getting close to what the finished room may look like so I've attached some pics below.

[Pulsar]

In the pictures you'll see that I plan to split room into 2 sections. The covered part of the room will be a small landing (stairs not shown on drawing) and will contain all of the equipment for cinema.

The basic construction of the loft has 2 pairs of purlins. The inner (higher) pair are around 6ft at the top making the space between them very usable. The loft is around 22ft long and between the high purlins about 9.5ft wide. I'm going to take the room out to the second, lower set of purlins as I think it will make the room feel bigger.

I've shown a screen approximately 8ft wide with seating situated 1.25 x screen width away. The seating position is somewhat dictated by the location of the the supports for the higher purlins which transfer the weight down to a brick wall below. My original hope was to remove these supports to give greater layout flexibility, but after investigation I don't think it is feasible without massively increasing the work required.

The screen wall end of the room is the party wall and as such I've planned to build out a chunky 0.5m false wall to allow for sound proofing etc. I've also shown the walls either side of the screen angled in. This is because I plan to use all 'in-wall' or baffle mounted speakers to give the room a very clean look. I also plan to use an acoustically transparent screen with the centre speaker mounted behind it.

The room is going to be 100% dedicated to watching content from a projector, so I'm going to make a true 'black hole'. Current plans show all of the walls are going to be covered in a black velvet/alacatara type material - probably over foam pads to aid sounds reproduction. There's still plenty of research to be done here.

[Pulsar]

The first stage of the project has been to remove all of the studding/insulation that the previous owner stalled. I'm quite close to finishing this now and will soon start laying the new floor joists. Using span table found on the 'net, I've calculated that I should use 7"x2" floor joists at 400mm centres. These joists are going to laid perpendicular to the roof trusses, above them (15mm clearance) using joist hangers at either end and bearing on the brick wall that the purlin supports attach to. I'll probably do another drawing to illustrate this better.

The second stage of the build is going to be insulating the room. I've decided to use the PIR type rigid board insulation (Kingspan / Celotex) in a between and under rafter installation (40mm between, 40mm under at right angels). On top of this I plan to use a laminate of 2 plasterboards (possibly soundblock) with green glue or similar between. This will exceed building regs for heat insulation of a loft conversion and hopefully keep the sound at bay (both outside coming in and visa versa). Again I'm going to be seeking your help with this so if anyone has done similar then please let me know your experiences.

There is loads more to come on this, I'll get some pictures of the actual room taken today and will post them up later. I had better get started on the work now or it will never get done.

Cheers

Rob

[deansocial]

are you sure it will exceed b regs for heat insulation, as from memory you have to achieve 0.19 which to do that you have to have between 110mm and 120mm of board to achieve this dependant on rafter centers. Not sure what impact doubleboarding has on u value but sure it is not much.

Has it been calculated for the extra weight of soundblock board to go on the rafters

[deansocial]

as for the joists is there any supporting walls running across the middle of the loft so the joists arerunning the same way as the existing ceiling joists as that way you can drop them between and gain that extra room. It is normal to use 7x3 or 9x3 for this, if you have the room you can even use ji beams(the i beams with osb web) and they reduce the sound transfer.

If you dont want to mess around with chicken wire between the joists for fire regs you can use firefly with is a fire proof matting.

[deansocial]

oh and you have to change all your doors for firedoor to comply to regs aswell

[Pulsar]

Originally Posted by deansocial

are you sure it will exceed b regs for heat insulation, as from memory you have to achieve 0.19 which to do that you have to have between 110mm and 120mm of board to achieve this dependant on rafter centers. Not sure what impact doubleboarding has on u value but sure it is not much.

Has it been calculated for the extra weight of soundblock board to go on the rafters

Hi,

I think you may be right. I haven't done the exact calcs yet and need to find out the U value for the laminated plasterboard. Using the celotex calculator I will get a U value of 0.2 with 40mm between and 70mm under.

Haven't checked about the strain on the rafters, will have to take a look - thanks for suggesting it.

Rob

[Pulsar]

Originally Posted by deansocial

as for the joists is there any supporting walls running across the middle of the loft so the joists arerunning the same way as the existing ceiling joists as that way you can drop them between and gain that extra room. It is normal to use 7x3 or 9x3 for this, if you have the room you can even use ji beams(the i beams with osb web) and they reduce the sound transfer.

If you dont want to mess around with chicken wire between the joists for fire regs you can use firefly with is a fire proof matting.

Hi again,

There is a supporting wall in the middle of the loft, but the roof of the house projects below the height of the end walls making it difficult to support the ends of joists running in the same direction as the ceiling timbers. Just to confirm, when you're in a bedroom the ceiling angles down for the last 2 feet at the outside wall - hope this makes sense.

I have been considering the manufactured i-beam / web joists (posi-joists?) but thought it might be better to stick with simpler technologies. Because my joists won't be in contact with the existing ceiling timbers I hope they will be fairly good at not transfering sound to the room below. This is where I got the span / size requirements for the new joists.

Load-Bearing Walls And Safe Floor Joist Spans

I plan to lay new insulation over the existing ceiling timbers, between my new floor joists so it won't be in contact with the ceiling plaster below.

I'm not actually going through building regs for the work for a number of reasons, but I do want to comply with all of safety aspects wherever possible. Therefore I am really grateful that you've taken the time to post these questions / observations.

Rob

[Magslad]

Hi Rob

Have recently completed something very similar (albeit an all-purpose room rather than a dedicated home cinema) - loft conversion in a 1930's semi with the screen (plasma in my case) on the party wall.

Link to my build is in my signature below if it's of any help. Ours was done under full building regs which you've said you're not doing so wouldn't necessarily need to do all the little bits, but a few inital thoughts for you:

- Under building regs all doors to any 'habitable room' in the house (bedrooms, reception rooms etc) would need to be changed for an FD30 fire door. Not necessarily a problem for you now but might come up if you sold the house
- Building regs would also require a mains fire alarm system on a separate circuit (with 3 interlinked alarms on ground/1st/2nd floor). Again not necessarily a problem in terms of living in the house but may come up if you sold
- For insulation on the loft ceiling, we avoided Celotex/Kingspan as the depth required to meet building regs means you lose a fair bit of ceiling height. Like you, we have good ceiling height anyway so not necessarily a problem but I wanted the room to feel as spacious as possible. So instead we used a product called Triso super-10 (pics of it are in my build thread). Total thickness was only about 15-20mm but meets all the requirements. Goes on like a tent then plasterboard over the top. Our loft was finished in December and I've had the heating on once since then (the days we had the heavy snowfall), so definitely does its job well. Under the floor we used Kingspan as depth isn't an issue here given the joists
- False wall on the screen wall definitely a good idea, I did this as well. Only about 25-30cm depth, filled with Kingspan, but I've checked with our neighbour and she has never heard any noise coming through
- Are you building access doors/hatches in the purlin walls for storage in the eaves? May not be an issue for you but we were very glad we did this given that by converting the loft we lost one of our main dumping grounds! Didn't do anything fancy, just boarded out with simple lighting then 5 access doors around the room, amazing how much stuff we can fit in there out of the way

Just a few initial thoughts there, from your thread it sounds like you're pretty much on top of what you're doing but if you have any questions I'm happy to help in any way if I can.

Cheers
Dave

[deansocial]

tri iso super 10 is no longer accepted for loft conversiond as it does not have a bba cert. I have used it on 3 loft conversions when it was accepted but was old on the lastit will no longer be accepted and true to there word when asked on the next job they said no chance.

As for fd30 firedoors you can simply swap for a 35mm firedoor now rather that swap the frames like we had to before they came out.

you more than likely will have to strap the new floor to the ceiling to replace the binders than run across unless you are above that height.

When you put the flooring down it is now regs to have it go all the way into the eves for fire regs

Soundproofing the party wall is a must to meet regs aswell as is adding 50mm celotex to the gable end(assuming its not hipped roof)

[Magslad]

Originally Posted by deansocial

tri iso super 10 is no longer accepted for loft conversiond as it does not have a bba cert. I have used it on 3 loft conversions when it was accepted but was old on the lastit will no longer be accepted and true to there word when asked on the next job they said no chance.

As for fd30 firedoors you can simply swap for a 35mm firedoor now rather that swap the frames like we had to before they came out

Triso super 10 approval must vary depending on the local authority - I know for certain that it is still approved and accepted for loft conversions in our local authority (know of one last week that was accepted), and not aware of any plans to remove that approval.

We didn't have to swap any frames when we changed our doors either - we just needed doors that had the FD30 rating.

[sdemmery]

Hi Pulsar,

Good luck with the project, I am in the midst of loft conversion I have a thread here http://www.avforums.com/forums/membe...t-hearted.html if your interested. Im trying to keep it up to date, but its manic here at the moment. Its going to be a master bedroom but the bed (Now built must update my thread) is a wall bed which when up will give me a room of about 4x5mtrs

I contemplated a basic conversion without building regs in fact I even started the job, but then changed my mind & felt I just wanted to do it via the official route. I got concerened about the "what if" situations (i.e. what if we have a fire in the loft no regs would mean now insurance payout, what if someone becomes trapped up there etc) The basic conversion has now evolved into a full conversion including full width dormer & bathroom! I also hung up my hammer on this one & got a great couple of builders in who are doing the whole thing. This was really difficult for me as I have always done all my own work on my houses. Still leaves me more time for tinkering with my AV setup oh & decorating

I think most of the other posters have covered a lot of the reg requirments even though you are not going down this route, but one thing I havent seen discussed is head height. If anyone is thinking of doing a conversion you need a minimum of 2mtrs this was the killer for me as had to lower all my bedroom ceilings putting in a new loft floor/1st floor ceiling, basically the top floor was gutted & we moved out for a week.

All exciting stuff, we are now back in the stairs are complete & the steels are going in next week. Anyway if I can be of any help please just shout, I spent a fair time studying the regs myself Im no expert but I may be able to help.

BTW The required U value is 0.2 I believe a rediculously low value, kingspan or celotex on its own is unlikely to acheive this alone we are using a mixture of TLX (Thinsulx) & celotex or something like this. The TLX is very thin & expensive but is a seriously good insulator.

Looking forward to seeing your progress.

Stu

[sdemmery]

Oh forgot to say, to work out the timber spans you need to get hold of the TARDA span tables. They used to be free but I believe you have to pay for them now. PM me if you need them

To give you an idea we needed a min of 6"x2 of C24 rated timber and could not span over 3.5mtrs. we do have a 7mtr beam but this is a Flitch beam (two 6x2's with 10mm plate between)

Cheers
Stu

[Pulsar]

Originally Posted by Magslad

Hi Rob

Have recently completed something very similar (albeit an all-purpose room rather than a dedicated home cinema) - loft conversion in a 1930's semi with the screen (plasma in my case) on the party wall.

Link to my build is in my signature below if it's of any help. Ours was done under full building regs which you've said you're not doing so wouldn't necessarily need to do all the little bits, but a few inital thoughts for you:

- Under building regs all doors to any 'habitable room' in the house (bedrooms, reception rooms etc) would need to be changed for an FD30 fire door. Not necessarily a problem for you now but might come up if you sold the house
- Building regs would also require a mains fire alarm system on a separate circuit (with 3 interlinked alarms on ground/1st/2nd floor). Again not necessarily a problem in terms of living in the house but may come up if you sold
- For insulation on the loft ceiling, we avoided Celotex/Kingspan as the depth required to meet building regs means you lose a fair bit of ceiling height. Like you, we have good ceiling height anyway so not necessarily a problem but I wanted the room to feel as spacious as possible. So instead we used a product called Triso super-10 (pics of it are in my build thread). Total thickness was only about 15-20mm but meets all the requirements. Goes on like a tent then plasterboard over the top. Our loft was finished in December and I've had the heating on once since then (the days we had the heavy snowfall), so definitely does its job well. Under the floor we used Kingspan as depth isn't an issue here given the joists
- False wall on the screen wall definitely a good idea, I did this as well. Only about 25-30cm depth, filled with Kingspan, but I've checked with our neighbour and she has never heard any noise coming through
- Are you building access doors/hatches in the purlin walls for storage in the eaves? May not be an issue for you but we were very glad we did this given that by converting the loft we lost one of our main dumping grounds! Didn't do anything fancy, just boarded out with simple lighting then 5 access doors around the room, amazing how much stuff we can fit in there out of the way

Just a few initial thoughts there, from your thread it sounds like you're pretty much on top of what you're doing but if you have any questions I'm happy to help in any way if I can.

Cheers
Dave

Hi Dave,

I had read your build thread previously, but I've just been through it again. I like the sound of the Triso and have just been doing some quick reading on it. Is that all you have used as insulation on the rafters in the loft? How does it perform at keeping the noise in/out of the room?

I'm not planning on having any storage in the eaves as the room will go out quite wide not leaving much space behind for storage. I know I'll probably regret it later, but I've found it quite liberating to get rid of loads of the junk we had stored up in the loft. In the small landing room I plan on using some of the eaves as storage for the AV gear.

I'll check on my doors, just replacing all downstairs ones as we speak and they have the exact same pattern as the ones you have (oak veneer?) not sure on their fire rating though. I do plan to install mains powered smoke detectors too.

I guess many people say 'we plan to stay here forever' when justifying not going for full building regs and I would say the same. However it is not just this, I really don't want a window in the room which I believe building rags would require.

Cheers

Rob

[Pulsar]

Originally Posted by deansocial

you more than likely will have to strap the new floor to the ceiling to replace the binders than run across unless you are above that height.

When you put the flooring down it is now regs to have it go all the way into the eves for fire regs

Soundproofing the party wall is a must to meet regs aswell as is adding 50mm celotex to the gable end(assuming its not hipped roof)

Hi,

The new floor will clear the existing binders (just as they are 7x2) but I need remove them so will use straps to the new joists. Not sure if this will transmit much sound?

Regarding the new floor having to all the way to the eaves, I don't think I am going to do this. I plan to go within a few feet, but the height between the new joist and the rafter if I fitted a further joist would be only a few inches. Don't fancy giving that a go.

I haven't decided what I'm going to fit to insulate (both sound and heat) the party wall yet. Any suggestions welcome.

Not sure why I have to use 50mm Celotex on the gable wall, all of the other walls in my house are just plasterboard on to the brick. Will have to think about that one.

Thanks again for the advice.

Rob

[Pulsar]

Originally Posted by sdemmery

I think most of the other posters have covered a lot of the reg requirments even though you are not going down this route, but one thing I havent seen discussed is head height. If anyone is thinking of doing a conversion you need a minimum of 2mtrs this was the killer for me as had to lower all my bedroom ceilings putting in a new loft floor/1st floor ceiling, basically the top floor was gutted & we moved out for a week.

All exciting stuff, we are now back in the stairs are complete & the steels are going in next week. Anyway if I can be of any help please just shout, I spent a fair time studying the regs myself Im no expert but I may be able to help.

BTW The required U value is 0.2 I believe a rediculously low value, kingspan or celotex on its own is unlikely to acheive this alone we are using a mixture of TLX (Thinsulx) & celotex or something like this. The TLX is very thin & expensive but is a seriously good insulator.

Looking forward to seeing your progress.

Stu

Hi Stu,

You've got a great project going there, I had already seen your Flickr pictures. I am very lucky in my loft with head height, I have a centre span of around 8ft x 21ft with 2m+ height. I wouldn't fancy lowering all of our ceilings on the first floor, sounds like a killer.

It looks like I need to do some more research on insulation as I'm getting a few mixed messages. As with most things I want to find a good mix of price / performance / depth - I'm sure I'll get there.

Cheers

Rob

[deansocial]

regarding the gable wall, it is just a matter of bringing it up to current regs which is something they require now. it is the same if you rendr the outside of a house(25%or more of total) you have to insulate to current regulation, not that anybody does because of the cost.

what depth ae your current rafters

[deansocial]

ebuild: Tri-Iso 10 no longer accepted by Local Building Authorities

[Pulsar]

Originally Posted by deansocial

ebuild: Tri-Iso 10 no longer accepted by Local Building Authorities

Morning,

An interesting thread there, thanks for the link. I've been using this site for some info and prices:

Insulation, Celotex, Kingspan, TLX, Actis, Rockwool, Gyproc, more

In the multifoil section they talk about building regs and the various types of multifoil. Here's an extract:

Which is better, Gen-X, Actis Tri Iso Super 10 or TLX Silver?
Gen-X – for and against
Gen-X mirrors the Actis and TLX Silver multi-foil concept, but at 33mm is 10% thicker
Gen-X is made in Britain.
Gen-X has less layers that Actis and TLX Silver , but one has to consider what is the benefit of the extra layers?
Gen-X manufacturers, Euroform, have done a great deal of research and development. And, have attained certification from both the BBA and BM Trada, and as such must be accepted by Building Control throughout the UK.
Gen-X is guaranteed for the life equivalent to that of the structure to which it is incorporated
Gen-X costs less than Actis Tri Iso Super 10 or TLX Silver
Gen-X does not require foil backed plasterboard in an under-roof installation, thereby saving in excess of £2.00 per board, excluding VAT
Gen-X's BBA Certificate specifies 75mm of PIR Board as opposed TLX Silver's 70mm.

It would seem that the Gen-X brand meets spec with an additional 75mm of PIR. If that's the case then I may as well go with all PIR considering the cost of the multifoil.

I wonder why multifoils were once accepted on their own but now require more insulation to meet the regs? If I'm honest I don't really care what the regs say as long I get a good solution for sensible money / space. Someone on the e-build forums seemed to suggest that Kingspan may have had a hand in changing the regs back to requiring PIR..... sounds dodgy to me.

I still have the question of the sound insulating properties of multifoil?

Interesting stuff anyway.

Rob

[deansocial]

i would say multi foil insulation has low sound proofing abilities as does kingspan to be fair. We used a product called phonewell on the last job for sound proffing the party wal but have no idea how well it worked as i did have access to next door

as for the kingspan versus multi foil. It all goes on what rafter size you have because you need 50mm airgap above the insulation(unless you have breathable felt on the roof) so if you have 100mm rafters you can only fit 50mm in between which would mean another 20-25mm under that then a batten to create 25mm airspace then multifoil then another batten for another 25mm then board or 50mm inbetween then 70-80mm under that then board(we batten before board to make life easy)

[Pulsar]

Originally Posted by deansocial

i would say multi foil insulation has low sound proofing abilities as does kingspan to be fair. We used a product called phonewell on the last job for sound proffing the party wal but have no idea how well it worked as i did have access to next door

as for the kingspan versus multi foil. It all goes on what rafter size you have because you need 50mm airgap above the insulation(unless you have breathable felt on the roof) so if you have 100mm rafters you can only fit 50mm in between which would mean another 20-25mm under that then a batten to create 25mm airspace then multifoil then another batten for another 25mm then board or 50mm inbetween then 70-80mm under that then board(we batten before board to make life easy)

Hi,

I'm more interested in sound proofing the room at rafter level to stop road noise coming in, although I will make sure the party wall is well insulated - it does already have 2 layers of brick to get it started.

Sorry for not answering this before, my rafters are 3 x 2 (75mm deep). However my roof does not have any felt at all, the tiles are just hanging on battens across the rafters. I'm sure I read somewhere that this construction method doesn't require the 50mm gap as it is well ventilated through all of the gaps in the tiles? I wasn't sure of this so I had planned on using 40mm PIR between joists leaving a 35mm gap. This can easily be adjusted to 25mm between and the remainder under the rafters if necessary.

This brings me to another point I'd like to check. Do I need a damp proof membrane in my insulation? I was planning on foil taping all joints where the between rafter PIR meets the rafters and also taping the joints on the under rafter PIR. Will this be sufficient with a membrane?

Again, I really do appreciate everyone's help with this.

Cheers

Rob

[deansocial]

i have alway quesioned why the 50mm air gap needs to be let when there is no felt and never really got an answer other than "because it does". personally i would use 70mm in between so no air gap then 40/50mmthen your board. the 40-50mm under will isolate the rafters from the pboards to improve sound proofing. No membrane is required and taping is not required but will improve the insulation and just looks a better job.

[Pulsar]

Originally Posted by deansocial

i have alway quesioned why the 50mm air gap needs to be let when there is no felt and never really got an answer other than "because it does". personally i would use 70mm in between so no air gap then 40/50mmthen your board. the 40-50mm under will isolate the rafters from the pboards to improve sound proofing. No membrane is required and taping is not required but will improve the insulation and just looks a better job.

Nice one, think I'll go this route then.

Thanks agian for the help.

Rob

[deansocial]

i would seriously consider getting a structual engineer in to look at the size of the rafters before you do anything first so you know what to do about the small rafters taking the weight. Explain to him the insulation you will use and the pboards and how many layers and he will work out where to go from there

[Magslad]

Originally Posted by Pulsar

Hi Dave,

I had read your build thread previously, but I've just been through it again. I like the sound of the Triso and have just been doing some quick reading on it. Is that all you have used as insulation on the rafters in the loft? How does it perform at keeping the noise in/out of the room?

I'm not planning on having any storage in the eaves as the room will go out quite wide not leaving much space behind for storage. I know I'll probably regret it later, but I've found it quite liberating to get rid of loads of the junk we had stored up in the loft. In the small landing room I plan on using some of the eaves as storage for the AV gear.

I'll check on my doors, just replacing all downstairs ones as we speak and they have the exact same pattern as the ones you have (oak veneer?) not sure on their fire rating though. I do plan to install mains powered smoke detectors too.

I guess many people say 'we plan to stay here forever' when justifying not going for full building regs and I would say the same. However it is not just this, I really don't want a window in the room which I believe building rags would require.

Cheers

Rob

Hi Rob

Sorry for delay in replying, have been out today.

From the later posts looks like you might have gone further anyway in terms of insulation research, but I'll answer anyway in case it helps. I agree with deansocial that Triso doesn't do much if anything in terms of soundproofing, this didn't really bother me as we're in a village so no real external noise comes in anyway unless the veluxes are open. The only wall I really bothered with in terms of soundproofing was the party wall - I didn't do anything other than build the false stud wall in front of the existing blockwork wall, and pack it with Kingspan. Our next door neighbour says she has never heard any noise coming through from the home cinema (albeit that she hasn't had her loft converted, but she's never heard any noise in the bedrooms etc so I've obviously done a decent enough job). The triso is indeed all we used on the rafters, then plasterboarded over the top of it. We already had felt behind the tiles, and there was plenty of air gap so all we had to do was get vent tiles put in to meet the requirements with respect to airflow. As you don't have any felt you wouldn't need to worry about vent tiles anyway.

Understand where you're coming from with respect to the storage. For reference our purlin walls are only 1m high (so that we could get plenty of width in the room) and it's amazing how much stuff you can fit behind them, but if yours are going to be much lower than this I agree you might not end up with much storage space.

In terms of our doors, yes these are oak veneer over a composite core, came from a company called Distinctive Doors and very happy with them.

You may be right in terms of building regs requiring a window, I'm not sure of the regs there and as we were having 3 windows anyway we didn't need to look into that. The thing I do know is that the older regs (whereby you had to have an 'escape window' in a loft conversion) no longer apply - hence the need for FD30 doors through the rest of the house and a mains smoke alarm system.

[Magslad]

Originally Posted by deansocial

ebuild: Tri-Iso 10 no longer accepted by Local Building Authorities

I don't want this to get into a "is Triso accepted or not" debate as it will drag Rob's thread off-topic, so I'll make this my last post regarding it.

The only thing I'd say regarding that link is it's pretty old (from late 2007), as you'll see from my build thread we did our loft conversion last year (Aug-Dec 2008) and were allowed to use Triso by the local authority. Our final inspection and certification was only a couple of weeks ago (we had some snagging that dragged on a bit) and they reconfirmed that Triso on its own was fine to meet the regs.

What it boils down to is that the interpretation of building regs varies from authority to authority (I was discussing this with my builder earlier today as we happened to meet up for a beer) - he works across 4 different authorities and each one has a slightly different interpretation of various parts of the regs. It could well be that Trisco is not accepted in the majority of cases (I don't know as I haven't researched it), but it is allowed where we are. Rob, if you're bothered about it I'm sure a quick call to the council would ascertain whether it would be accepted in your area or not - if you're not bothered and not going through regs then just use the product you think will be best for you. Either way you're going to be improving the insulation in your house which is no bad thing.

Dave

[sdemmery]

Hi Pulsar,

Even though you are not doing the building regs thing I would suggest taking lots of pictures should you need them for referance in the future of course if you do everything right you may be able to file a retrospective building regs application should you want to?? Ive read that when selling the new homebuyers pack you have to provide forces you to disclose something like this, but as you say if you have no intention of moving come 20years time im sure it will be all different anyway.

I was also going to mention the air gap with the insulation, ours is being done as a "Warm Roof Constuction" All tiles & felt removed, tlx laid on outside, then refelted/tiled & 100mm of insulation on the inside. Our roof beams are 75mm X 50mm & are having to sister 50mm X 100mm to them, structural engineer says the existing beams would not take the weight of the plasterboard & maybe a few tonnes of snow in the winter. Arround the 3 front veluxes we are also having extra strengthing put in.

As for sound proofing, I built my own recording studio a few years ago, it was a room in a room (block built) but I used Rockwool RW3 on the inside to, its a really good product I had a full drum kit in there are it was only just audible at 100ft away. RockSilk is slightly cheaper & as good. I had intended to sound proof my new floor with 150mm of Rocksilk but the budget wouldnt stretch so Im just doing the party wall with 50mm of Rocksilk & double sound shield 12.5mm plasterboard. I understand that sound proofing of this sort does little to reduce the bass frequencies anyway which was my main aim. Im going to try putting my sub on a thick piece of granite to see if that helps. I ended up cramming 300mm of ordinary rockwool in the floor seems to have made a big difference already & I dont have any boards down. I am also going to use some of that green sound insulating board used under lamitate flooring onto of the finished floor taping all the gaps up & sealing around the edges I read on the forum that someone has tried this with some success & it is pretty cheap to do.

Can I ask why you dont want any roof windows? You might need some ventilation up there in the summer. Im fitting the velux windows with black out blinds & the main dormer window is having an electric curtain track with blackout curtains, Im hoping this will not let any light in having said that I will most likely use the projector only at night anyway.

Cheers
Stu

[Pulsar]

Originally Posted by deansocial

i would seriously consider getting a structual engineer in to look at the size of the rafters before you do anything first so you know what to do about the small rafters taking the weight. Explain to him the insulation you will use and the pboards and how many layers and he will work out where to go from there

I'll take some advice on this as you suggest. I've sort of planned on having an extra 100mm depth on the joists with insulation & sound proofing so I could add say 50mm x 50mm to strengthen them? I'll investigate this a little more I think.

Rob

[deansocial]

Originally Posted by Pulsar

I'll take some advice on this as you suggest. I've sort of planned on having an extra 100mm depth on the joists with insulation & sound proofing so I could add say 50mm x 50mm to strengthen them? I'll investigate this a little more I think.

Rob

the norm would be to bolt an extra rafter to the side of the existing rafter. You need continuos insulation under the rafters to stop cold bridging.


last post from me regarding tri iso, I know what your saying about different authority but round here the areas i work in dont accept products without BBA certs but for some reason they did will super 9 so as normal a big contradiction

[Da_Rude_Baboon]

Originally Posted by deansocial

last post from me regarding tri iso, I know what your saying about different authority but round here the areas i work in dont accept products without BBA certs but for some reason they did will super 9 so as normal a big contradiction

I will chip in on this briefly as there has been some mention of this in the self build magazines. The certificate was suspended as the other insulation manufacturers questioned the testing methods used on multi-foil insulation and claimed its performance drops significantly when exposed to winds. Until new tests are carried out to see if this is correct and the results approved by the regulatory body the certificate has been suspended.