Insulating under-house garage?

Hi my house sites on top of the garage and has an open stair and hatch doorway into our living toom. Whats the best way of insulating between my garage and room? Ive been told insulating the garage door is a waste of time and i should concentrate on the connecting door but want to know if anyone has any other suggestions that wont mean i have to buy/make a new door.


Vyger4 years ago
Your from the UK so this is not typical American construction. Also older structures there don't tend to be insulated very good. You basically are going to need to seal off the source of the cold. It is coming from both convection, the moving of the air and from conduction, going through the floor. If is legal to use foam insulation there, something like Celotex with foil on each side will work. Get some 1 1/2 inch Celotex and screw it to the ceiling of the garage (the floor of the house) and then cover it with 1/2 sheet rock.  This helps to fireproof it.  This will prevent the heat from going through the floor and into the garage.
Not sure what your stair way looks like but you might have to enclose the hatch and the stairs in some way to make an air lock type of hall. You don't necessarily need a second door if you don't have a lot of wind. You could get by with a heavy plastic curtain that slows down the air flow. 
Vyger Vyger4 years ago
Just a second thought, If you don't want to do something permanent for the door and don't care about looks, you could make a hallway out of heavy sheet plastic. A light wood frame with the plastic (or tarps) stapled to it would be enough to prevent air movement. They make green houses out of the stuff so it would be tough enough. You could remove the plastic in the warmer months. It would not look that great but it would give you a way of trying out an air lock system to see if it works without actually having to build something permanent now.
Is the interior of the garage finished? Do you have insulation in the exterior walls and the ceiling?

If the answer is yes to the above questions then you should focus on the garage door. Seal off any air gaps you can find as best you can. If you're still having trouble with temperature differences then you may need to get a better insulated door.

If the garage isn't finished (i.e. you have bare studs showing) or you don't know if it's insulated or not then that is the first thing that needs to be tackled so that cold air stops making it's wain into the rest of the house.
Some garage doors are like a screen door in a submarean and some are not, go around the garage door with a candle if you find wind you got your answer. Put in a living room door and insolate the floor. If you don't find wind insulate the garage door and walls.