Building Regs advice - Garage Conversion

[RAMONJKD]

FINISHED!

I will take some better photos this week as LG Secret cameras are terrible......................

[duffy78]

Originally Posted by RAMONJKD

Hello there, I have been given planning to convert my Garage, and am now tackling Building Regulations..... I have been asked to clarify a few items by building contol and would appreciate any assistance or advice....

They have asked the following things:-

Details of damp- proofing to walls and floor
Can a mebrane be laid under the floating floor or is painting a sealant easier?
Also, will the single skin wall need painting as well?

Background ventilation part F1
Can this either be covered with a vent in the wall or trickle vent in windows?

Heat loss through walls should not exceed 0.3 W/m²K, Floor 0.22W/m²K & Windows 0.18W/m²K
I did this at college but was wondering if anyone had ideas of construction to cover this? I was intending to stud out the walls and fit Celotex but am not sure of the type to use. I was also going to stud the floor and inlay with celotex as well. The Window details i'm assuming i can obtain from the suppler.

Thanks for any assistance or advice!

Clive

try running these past your inspector.

FLOOR CONSTRUCTION
65mm THICK SAND CEMENT SCREED (REINFORCED WITH FIBRE OR D49 MESH) ON 100mm THICK ROCKWOOL ROCKFLOR INSULATION TURNED UP 300mm AT EDGES OR SIMILAR ON 1200 GRADE VISQUEEN DPM ON SAND BLINDING ON EXISTING ASSUMED 100mm THICK CONCRETE SLAB (THE BUILDER SHALL ALLOW FOR THE BREAKING OUT OF A CORNER TO VERIFY THE SLAB THICKNESS TO THE SATISFACTION OF THE BUILDING CONTROL OFFICER)


WALL CONSTRUCTION
SINGLE SKIN BLOCKWORK INSIDE OF GARAGE TO BE INSULATED USING KINGSPAN K18 KOOLTHERM DRYLINED INSLUATION BOARD, OVERALL THICKNESS TO BE 67.5mm INCLUDING 12.5mm PLASTERBOARED TO GIVE TOTAL U VALUE OF 0.3 w/m2k

they should do you fine.

and your right about the windows, just spec the u value when you order them.

[RAMONJKD]

Nice one! the only issue i may have with the flooring is that i was hoping to keep the thickness to a minimum, Basically the slab of the garage is about 50mm lower than the adjacent living room floor, so was hoping for perhaps a slight step up via a threshold rather than a step.......

[duffy78]

HI again, bored at work so done some digging for you.

The u value you've been told you need to acheive with your windows is .... well to put it bluntly unacheivable.

Luckily for you you've been told wrong, you need a U value of 2.0 for pvc windows.

Your floor u value wants to be 0.25 as well. if you tell me the overall size of the garage, length x width i can do a quick perimeter / area comparison and come up with a more accurate thickness of insulation rather than just picking it out of a table.

[RAMONJKD]

The Garage is 5500*2500mm, Does building regulations state the required window values?

Thanks for the info, its a great help! I will be sure to provide regular updates once i get cracking!!

[duffy78]

you could probable get away with celotex TB3030 with the perimeter / area ratio you have given me, thats 30thk but you'd still need the 65 screed,

you could push it with the TB3020 to gain you another 10mm but its prob best not to.

Building regs state u values for all elements of an extension.

Of course if you want a level floor from living room to garage conversion you could always break the garage slab out, wouldn't add much to the overall cost, prob £500 for the slab and you'd be getting the insulation anyway.

[Designs]

Originally Posted by duffy78

you could probable get away with celotex TB3030 with the perimeter / area ratio you have given me, thats 30thk but you'd still need the 65 screed,

you could push it with the TB3020 to gain you another 10mm but its prob best not to.

Building regs state u values for all elements of an extension.

Of course if you want a level floor from living room to garage conversion you could always break the garage slab out, wouldn't add much to the overall cost, prob £500 for the slab and you'd be getting the insulation anyway.

Your local authority seem to be enforcing different 'u' values to around here. He may be able to avoid screed, It would be cheaper and easier to have a floating floor. Lay 1200 gauge dpm (or asphalt), lay the insulation and then a layer of chipboard on top.

Now as they have asked for damp proofing to the walls, I’m guessing this is a single skin garage and it’s to prevent the ingress of driving rain. You may be required to Cinter Proof the walls which is a horrible job! You’d have to paint it on. It may be best to provide an internal leaf of timber studding with 100mm of Celotex/Kingspan in between voids of timbers. It would achieve a ‘u’ value of 0.3 and the cavity would prevent damp coming through the wall without having to bond the insulation to the masonry.

As for the windows, all they are asking is for the glazing to be 16mm thick, low-e coated and filled with argon. The window manufacturer will spec all that though (leave stickers on until building control inspect to prove adequacy). Trickle vents are fine too.

Might be best to get some bespoke advice form a local architectural practice though as they could come out and see everything. Good luck!

[mhuk05]

Have you spoken to your Building Control Officer and asked him what he'd recommend/ like to see (especially as it's him/ her that you'll have to please)?

There's also plenty of practical advice on diynot.com

[RAMONJKD]

Thanks for the response guys. It will be good to resolve all the issues now so i can then just crack on with the conversion.Unfortunately the building inspector didn't seem overly keen to advise on what i should be doing, he just kept refering to what he's asked for rather than specific solutions. The floating floor possibly sounds more practical. I've roughly set a budget so that i've hopefully got cash left over to update some of my kit!

I will try him again and run some of these ideas past him to see what he says.

Watch this space!

[duffy78]

Originally Posted by Designs

Your local authority seem to be enforcing different 'u' values to around here. He may be able to avoid screed, It would be cheaper and easier to have a floating floor. Lay 1200 gauge dpm (or asphalt), lay the insulation and then a layer of chipboard on top.

Now as they have asked for damp proofing to the walls, I’m guessing this is a single skin garage and it’s to prevent the ingress of driving rain. You may be required to Cinter Proof the walls which is a horrible job! You’d have to paint it on. It may be best to provide an internal leaf of timber studding with 100mm of Celotex/Kingspan in between voids of timbers. It would achieve a ‘u’ value of 0.3 and the cavity would prevent damp coming through the wall without having to bond the insulation to the masonry.

As for the windows, all they are asking is for the glazing to be 16mm thick, low-e coated and filled with argon. The window manufacturer will spec all that though (leave stickers on until building control inspect to prove adequacy). Trickle vents are fine too.

Might be best to get some bespoke advice form a local architectural practice though as they could come out and see everything. Good luck!

to attain the u value the particular insulation ive spec'd needs the screed, the floating floor he's back to using something like 100 thk insulation. in my experience the screed gives a nice solid floor whereas the floating timber does not.

and as for my local authority requiring different u values, well my local authority use the building reg's, dont yours?

[Designs]

Originally Posted by duffy78

to attain the u value the particular insulation ive spec'd needs the screed, the floating floor he's back to using something like 100 thk insulation. in my experience the screed gives a nice solid floor whereas the floating timber does not.

and as for my local authority requiring different u values, well my local authority use the building reg's, dont yours?

True, a solid floor is often best but it's difficult to advise when you don't know what the rest of the build is or what budget requirements are. The rest of the house could have a timber floor or even a floating floor anyway and if it was carpeted you wouldn't be able to tell much difference, if any. You'd only need about 75mm of Celotex, not 100mm.

As for my local authority, they usually have their head up their arse! I use a fair few and tbh they are all in line with what the op said
"Heat loss through walls should not exceed 0.3 W/m²K, Floor 0.22W/m²K & Windows 1.8W/m²K"

To the OP, give a different LA a call, some are useful and some aint.

[duffy78]

looks like i'll need to purchase some new building regs,

im still using the 2000 L2 document, i stand corrected.

[duffy78]

Ok design, clarrification please,

Document L2 april 2006, latest issue?

standard u values of construction elements is still as follows,

Table 1 Standard U-values of
construction elements
Exposed Element U-value
(W/m2K)

Walls, including basement walls 0.3

Floors, including ground floors and 0.22
basement floors

[Designs]

Yeah, that’s the latest issue. They are all free to download from planning portal. The only other changes are ceilings need to be 0.16 if it’s a flat roof or 0.2 if it’s a sloping ceiling with some insulation under rafters to prevent thermal bridging. Also semi exposed walls such as next to an internal garage now have to be insulated to the same 0.3 ‘U’ value (this may be pre-existing though).

[dazzarooney]

i would highly recommend you visit the celotex website - www.celotex.co.uk..there is a u value calculator.

if the walls are single skin applying a layer of celotex to the wall internally (thickness is dependant on the u value you require) tape the joints with celotex tap, appy vertical battens then plasterboard over...you need to ensure the wall has a horizontal dpc..if not it can be injected.

the thickness of the insulation is dependant to the permiter/area of the garage..again the celotex website has more info on this...most new garages will already have a dpm you need to investigate to see if yours has..if not..you can either use a 1200guage polythene or a liquid asphalt (paint)..synthaprufe or RIW LAC....trouble with the paint ones they smell..and the smell will never go away...if you go down this route..ie..paint over existing slab, insulation, vapour barrier..i would highly recommend a minimum 65mm sand cement screed..alternativly if you already have a dpm under ths slabe..or you wish to go the polythene route..you route would be insulation, vapour barrier then 22mm t&g flooring grade chipboard....if your going to tile the floor..i would recommend the screed..if its carpet or floor board/laminate..the chipboard route is ok

the windows..if your having upvc can easlily acheive 1.8 u value....and if they are new windows get them to put in trickle vents..each habitalbe room needs to have 8000sq.mm of back ground ventilation.

above all, look at the celotex website...or feel free to pm me for clarification..i dont usually visit this side of the forum often.

hope this helps