Best board to line a ceiling in ia town house garage

[4rchibald]

We live in a town house with 2 garages. Living area is located above them. Ceiling in both garages is lined with a white board (looks mineral). The problem is that because it's quote old with only some insulation, our house gets really cold with draughts from every possible hole in the wooden floor.

We decided to insulate the floor again with mineral wool, but I'm not sure what to use to replace the existing boards. These are nailed and at least some will get damaged during removal.

My first idea was to use plasterboard, but I'm concerned about moisture (no heating in both garages).

I would appreciate a word of advise what't the best to line a ceiling.

 

[Tipper]

Mine is similar and is lined with plasterboard.

It needs to be double layered with overlapped and taped/sealed joints for fire resistance.

Incidentally I insulated with blown fibre into the joists space through 100mm holes using recycled newspaper, sorry can't remember its trade name. Does a great job but a little pricey. It saved having to replace all the plasterboard, just needed repairs and fire sealing.

Edit: Found it now, 'Warmcel'

 

[ryanhirst]

Tipper is right here

 

[4rchibald]

Thank you. Boards used in my garage are not double layer so I think I'll invest in proper plasterboard.
I wanted in remove the boarding and old glass wool and replace it with layer or insulating wool and then wedge polystyrene sheets (25mm) between the joists (with expanding foam where required) and cover with plasterboard.

Do you think that should be enough or is there any draught / moisture control required like backed plasterboard or any similar?

 

[stableroofer]

If your concerned about moisture from the double garage there's nothing stopping you having the second layer of board being moisture resistant.

Personally i would have the top layer of plasterboard with foil backing to reflect as much heat as possible back into the upstairs.
Also for the cost of poly insulation aswell as rockwool i think the costs outweigh the thermal values.
I would save the money and get as much rockwool in the gap as possible 200mm blanket should squash in nicely, especially with the subsidies on it at the moment.
Dont worry about trying to seal holes, the new plasterboard ceiling will do the sealing.

 

[TheVictorian]

Why not leave all the existing materials in place and fix some 50mm+ celotex sheets to the ceiling - it won't look amazing, but it's a garage.

 

[4rchibald]

Thank you.
Yes, the cost of polystyrene, wool and new plasterboard is massive, but I'm having problems with heating. While air temperature is around 21-22, the floor is much colder.
I would have to check the insulation values of both materials and compare it to values of the standard wall. I'm happy as long as it's above.

TheVictorian - this was one of the ideas, but the cost of celotex is more than a poly and I'm little concerned about fire resistance. I use garage to do repairs so there's always a risk of odd spark here or there.