Insulated Internal Cladding of an outside Garage

[PeterJCW]

Insulated Internal Cladding of an outside Garage


I am in the process of refurbishing my outside garage, which has one external door and a typical normal garage door. I have read about the problem of damp and am concerned. I am proposing to put Self leveling compound on the floor to seal the bare concrete (45 years old) and then cladding the walls with shiplap. I think that the easiest insulation would be foam boards,. I am wondering how to damp proof it in order to prevent the project going pear shape with lots of mould etc. The roof is flat and uninsulated.
I have looked on lots of sites and got confused as to the best solution...
Any suggestions would be greatfully received. Thank you
Peter

 

[jeds]

Are you planning on heating? Damp isn't normally a major issue in garages because of the high level of natural ventilation. Once you start enclosing cold walls within cladding etc, you might create a monster. What is the planned use?

 

[PeterJCW]

Thank you for your reply...To use as a workshop. with fairly regular use and yes to heat it when I am using it. I was proposing putting the cladding on the inside walls not the outside...

 

[jeds]

The important thing is to prevent moist air getting to the cold side of the insulation. A good plan would be too insulate (PIR foam would be a good option) but then fix a vapour barrier before fixing the final cladding. 1000g poly is suitable. Maybe the same treatment for the ceiling. The floor would be better with some level of insulation, even if it's 25 or 30mm. Finish with chipboard floating floor over. Glue the joints. No fixing required.

 

[PeterJCW]

Thank you Jed for those suggestions.... My concern for the floor is that the level of the floor is the same as outside, so to add insulation to the floor will create a step. as I plan to still use the door, I am concerned re that rain will easily come in and under the floor as a result.... I had thought of pvc squares on top of the levelled floor...?

 

[jeds]

You could provide a barrier at the door - and/or grade the floor off if you want to keep it level at the threshold. If the floor is tricky, it is less critical compared to the walls and ceiling, but insulation will reduce - or eliminate - condensation, which I think will be your biggest problem.

 

[PeterJCW]

That is very helpful. I am unsure how I would grade the floor or what sort of barrier to use, whilst still maintaining watertightness? sorry for all the questions but it will lhelp me get it straight in my mind. There was talk re the cls timber to put a damp proof membrane between it and the wall. Good idea??

 

[^woody^]

Have you searched any of the numerous garage conversion threads? All this is basic stuff and described in many posts.