Insulating a single garage conversion better?

[pablopete80]

Hi all

When i bought my house the single garage had been converted into a room and unfortuantly along time ago so is not insulated. I am now planning to insulate it and make it a bit more usable. I do however have a couple of questions i thought someone may be able to help me out with.

Its a centrally heated room (6.7m x 3.2m) with 2 D/g units and a D/g pvc door. 1 Internal door and a flat roof (ventilated bu no insulation). It only has a 1m party wall with the main house so all walls need doing.

What i have planned is to rip off all existing dot and dabbed plasterboard and chipboard ceiling. So when adding the insulated stuff it doesnt soak up the condensation.
Attach 40mm insulated plasterboard to the joists leaving the existing 100mm gap for ventilation and stopping short of the walls by 20mm to aid ventilation of them (the walls)
batten (50x25mm) the walls @600 centers.
Screw 40mm insulation to the battens.

Now the questions. As its not going to be a main living area just a games room i have not added a vapour barrier as its well ventilated and wanted any moisture to be able to escape out though the p/board and bricks if needed. Is this ok as i have read various advice on this?

Can i gripfil the battens to the walls instead of screws, allowing 24hrs to set before attaching p/board.

Do i leave a gap at the bottom of the walls to aid ventilation or is it enough at the top only?

Dont worry the floor is good so does not need sorting.

Oh and if its all completely wrong please advise on a suitable solution.

Cheers

Pete

 

[angelboy]

I would think you'd need to insulate the floor as well and raise it above the DPC.

 

[pablopete80]

The floor is already done and sorted.

My main question is will gripfill be ok to hold the battens?

Pete

 

[Tusses]

I think you should have a vapor barrier.

 

[Dibs-h]

With your walls - why not just fit insulated plasterboard to the walls? What is gap going to achieve? Insulation (polystyrene or PU foam) is vapour impermeable so moisture from the room will not pass thru it.

 

[jasonB]

Dab the insulated PB onto teh walls saves having to fix battens, gives the airspace and sticks far better than gripfill.

If you still want to use the battens then don't gripfill them.

As said the foam backing will stop vapour transfer.

J

 

[Lons]

Hi Pete

You haven't said whether your external walls are single (1/2 brick) or cavity construction.

This is important as it dictates whether or not you need to prevent damp / water ingress. cavity wall will need no special treatment and you certainly should not require the ventilation gap you suggest.

1/2 brick single wall which is more likely, needs completely different treatment for a habitable room and would not have obtained building control approval when it was converted. Best way to approach that is to treat it like a timber framed construction and install vapour barrier, insulation, frame and plasterboard. You would sacrifice a little space but straightforward.

A single wall, unless rendered will always have the potential of transmitting moisture to the inside during prolonged or driving rain as most bricks are porous as is the mortar bed. As they are also cold, any internal moisture will condense on the surface.

Bob