Evening all. Our house is a relatively new build being around 10 years old but is a common mass produced McLean detached property. However, we love where we live and wouldn't move for the world. So to the point of the post. The property has an integrated garage below a bedroom, currently it has an uninsulated steel garage door, the bedroom above is separated with two layers of plasterboard and rockwool between the joists. The internal walls of the garage seem to be a whiteish soft and light-weight block, the garage is also where the non-condensing gas boileris located. An internal door leads from the garage to the hallway. I am sure this is the worst area of the house for heat loss so the first thing to tackle, so should I treat it as external to the envelope, internal or hybrid? I have a electronic thermometer recording 24x7, currently it is reading 13.5 deg C, internal temperature is 20 deg. C and externally 0.5 deg. C

Thanks all,

Paul

Hi Paul

The garage should be thermally seperated from the rest of the building, I.E, treated as if it were outside. So all of the walls and ceilings between the garage and the house may allready be insulated to the same level as the rest of the external enveope. Not sure of this became compulsory in the 2002 or 2006 version of Part L. I would drill a hole in the wall from the garage side to confirm


Some other points to consider:

Are the pipes from the boiler well insulated?

Can you improve airtightness?

Insulate ceiling and walls to U=0.1 or as close as you can get to it

Seal all the tiny gaps an cracks everywhere between the garage and the house.

Check the party wall cavity between you and next door for heat losses too.

Thanks all for the advice. If I'm aiming for U=0.1 how do I get down to that level? Based on what I know the current construction is 12mm plasterboard (0.14 Wm/K) and 160mm lightweight block (0.2 Wm/K). I'm assuming the best insulation would be PUR with a value of 0.022W/mK? At a thickness of 100mm I would still be some way off a U=0.1?

Paul

Resurrecting an old thread rather than create a new one because I'm now in a position to start work.

I would ike to improve the insulation of our integrated garage to reduce heat loss from the house into the garage. My understanding is that I should consider it external to the building envelope. Current consruction appears to be lightweight block from garage to house followed with dot and daub plasterboard. The improved insulation is to go on the garage so external to the main envelope but the garage contains a tumble dryer, which although externally ventillated is likely to increase humidity. Plan to date is to lime parge coat the lightweight block for airtightness followed by insulation, then fermacell panels. Originally I was considering PUR insulation but having read a few threads I'm a bit concerned about condensation. So what would be best based on relative thickness and condensation risk, PUR, EPS or something breathable like Diffutherm / Pavadentro, would I need a vapour barrier?

Paul

The garage is not quite the same as outside it is sheltered and retains some heat, it is a poor idea an integral garage.

Air seal everything, then insulate as much as you can, presume the house is not passivehouse? so I will go with Mike or a bit better you 100mm sounds OK.

Paul, is the garage still in use for its intended purpose, if so could I suggest insuring that any insulation that is installed and that could be remotely flammable is faced in a non flammable board (possibly 2 layers of plasterboard). Sorry if this is blindingly obvious.