[Noel]

Hi guys,

I see a lot of people have done garage conversions but I can't get an idea of how you're treating the floor. My garage is detached and has a concrete floor with the plastic membrane but no polystyrene underneath. My builder says I can lay a laminate floor or carpet directly on top (with appropriate underlay, obviously, but I think I'll need to build a "stud" type sub-floor and insulate it, otherwise I'll lose all heat through the floor. What's the consensus?

Thanks,

Noel

75mm celotex rigid insulation with 19mm t and g chipboard will give you a good floor which meets current building regs spec

have fun and prepare to be totally tired out as am I

[Noel]

Thanks Thommo. Is Celotex a fixed shape polystyrene type insulation or a flexible one?

Cheers,

Noel

[Ste7en]

I opted for Kingspan as opposed to Celotex as its foil backed on both surfaces (!)

I'm guessing this will make heat retention better and keep cold to a minimum... I hope

[Noel]

Thanks Ste7en,

I have been advised by the local builders merchants that I can put in a "floating" floor - i.e. 50mm of polystyrene with a layer of chipboard over it. This seems sensible and fairly easy to do - any reason why I shouldn't?

Cheers,

Noel

[neilball]

I'd recomend Dow Floormate (styrofoam boards) as these are much more resiliant compared to celotex/kingspan or jablite/polystyrene - you can walk on the floormate without much risk of damage whereas the others tend to break up very easily. The foil facings on the celotex/kingspan can help reflect radiant heat in roofspaces but has no benefit under your floor. AFAIK the foils main use is to make manufacturing easier.

[woody67]

Kingspan and Celotex are brand names for almost identical products.
As a rough guide, 50mm celotex equals 75mm stryrofoam or 100mm polystyrene.

These boards are equally effective in compression under load/under floorboarding and none will break up any more than another.

The main issue with garage conversions is the height from the new floor to the ceiling. If height is limited, then a thinner, more efficient board is need but costs more. Thinest of all (and most expensive) is Tri-Iso Super 10 - less than 10mm.

[Ste7en]

Originally Posted by Noel

Thanks Ste7en,

I have been advised by the local builders merchants that I can put in a "floating" floor - i.e. 50mm of polystyrene with a layer of chipboard over it. This seems sensible and fairly easy to do - any reason why I shouldn't?

Cheers,

Noel

I'd be wary of using 50mm of polystyrene. The building regs guys in my area told me that 100mm of polystyrene was their MINIMUM requirement.

When they found out I was using Kingspan they said that 75mm would suffice.

This 'could' be to do with compression over time.

Never heard of Dow Floormate, but it sounds pretty good.

[Noel]

Thanks for all the responses guys, I have just ordered 12 Celotex Kingspan boards from here http://cgi.ebay.co.uk/CELOTEX-KINGSP...QQcmdZViewItem to be delivered next Monday.

I spoke to the guy when I ordered and he suggested it's not a good idea to use Kingspan/Celotex under chipboard as a floating floor as he'd be worried about movement....anyone actually done this and happy with it?

Also the building regs bit intrigues me. Do I have to have building regs? The garage is detached, about 15 metres from the house and the conversion is for my own benefit (I've even made the stud wall easy to take down to convert the room back to a garage if necessary). The only thing I intend to have any certifiation for is the electricity, and I will have the relevant certification for that.

Thanks,

Noel

[Ste7en]

18 sheets! It must be a big garage!

Oh, 50mm... you're going to double up I suspect. Still, not a bad price and it'll be nice and toasty.

I assume chipboard wouldn't move any more than weyrock, but I could be wrong.

I used a damp proof membrane, then Kingspan, then weyrock and the floor is rock solid.

[Noel]

Hope it's 12 sheets....

The garage is 6mx5m internally. I don't intend to double up, but could change to 75mm tomorrow if necessary - do I need 75mm Ceoltex or would 50mm be OK?

Thanks for the response,

Noel

75mm meets current building regs with regards to heat loss.

also if going down building regs route , you really should get all your construction approved before you start, else costly when they say no, regs cahnge all the time espec heat loss and this all needs to be professionally calulated before you dive in.

also a good reason for building regs route is that youll probally have a few grands worth of gear in there, will your insurance cover you if its still classed as a garage, most policys only allow £1000 worth of cover in a garage, shame to loss all that hard earned gear if you got burgled or a fire.

If you sell you advertise also with this habitable space.

[Noel]

Thanks again for the response Thommo, very useful info.

no problem