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Damp Proofing

Garage conversion

Hi I have a garage with access door into kitchen the garage was converted into (Garage Conversion) the builder put timber battens on the walls put polystyrene foam slabs not Celotex in and plater boarded on top and then skimmed as well. The floor is concrete I put carpet undrelay with carpet on top. The conversion was done about 9 years ago and I have been suffering since then with freezing temperatures the bedroom above the garage is also freezing I read online that if a Bedroom is above a garage you should put insulation in the floor boards which I did buy lifting all the floor boards and stuffing with Earthwool insulation. But still the bedroom is cold and the garage I am sick and tired as wasting money on heating also to mention I have mould in the garage. Is there any body out there who can advice on how to make the garage and bedroom warmer. Many thanks hope to hear from somebody.

Hi Billy the house was built in 1932 and all of the house has timber floors except the garage which is concrete there is no vapour barierr there are two doors one is a UPVC one which leads into the garden and the other is timber which leads into the kitchen there is also one window which is also double glazed. There also no DPC the walls are solid double walls.

Thank you hope to back from you soon.

3 Answers from MyBuilder Damp Proofing Specialists

Best Answer

hi moedinn,
what decade was your house built in? if your house is old theirs a possibility they wont ben any insulation/vcl (vapour control layer) beneath your concrete slab which could be causing the mould and definitely not helping the temperatures, also do you know if you have any cavity insulation in your exiting garage? and any old windows or doors in the garage that aren't up to current British standards? is their also a current DPC (damp proof coarse) in your existing garage, they could be multiple things to approach but without knowing anything personally about the property theses are a few things that may be causing problems, if you need any advice on what direction to take id be happy to point you the right way!
cheers billy


Answered 12th Dec 2017

Should have insulated the garage with celotex or kingspan as old external walls are now internal walls. Mould is caused by condensation on the cold non insulated walls. Also new plasterboard should be 50mm off of old concrete screed, and concrete should have had a liquid dpm (damp proof membrane) applied and possibly new dpc injected with cream. Aswel as insulation it should have a bit of ventilation put in to allow air flow or room will sweat. Easily rectified by reboarding over with celotex plasterboard where it is already attached to the back of boards, then re skimming following all points above.


Answered 11th Jan 2018

If you have mould then you have a condensation issue. This is caused by an imbalance between your heating and your ventilation. i.e. not enough of one or too much of the other.
If you are saying it is too cold directly above the garage then the answer would appear to be a lack of insulation. You should certainly have the walls and the concrte floor insulated to building standards. This may not be possible of course due to floor levels but as others have pointed out, if you have concrete, you need a damp proof membrane. The wallplaster may have to come off too to install the additional insulation. Not an easy one unfortunately. Other elements to consider are whether or not your window has trickle vents - which they should and the size of the radiator in the garage - has it been specified as correct for the size of the room?


Answered 12th Apr 2018

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