The bare necessities

[rab]

Hi guys,

 

It's silly question time, but you're used to that with me.

 

I'm in the process of creating a layout space over my garage.

I won't go into all the details as it's a bit complicated but,

I'm beginning to think about insulation between the garage,

(which is not going to be that warm) and the space above.

I've fixed joists at 400mms ctrs, and was thinking about using

Celotex type insulation between the joists.

 

As the space below is only storage, ( I don't keep the car there),

I don't need it to look tidy, so from that aspect I don't need to

board over the bottom of the joists (I will be boarding over the tops).

Can I just stuff insulation between the joists and leave it to that. 

The advantage I can see is I don't have to worry about

condensation build up.

 

Would there be any advantage in boarding over the bottom, 

and if so, can I get away with using plywood rather than plasterboard.

 

As you can see I'm looking for the easy option, hence the topic title.I

 

Over to you.

Edited April 4, 2020 by rab

[Siberian Snooper]

In our club room, we strung 2 x 2 joists across the room at 20 inch centres and put 8 x 4 sheets over the top and fixed it using aluminium tape and also sealed the joints with it. It reduced our winter heating bill by around 50%, we meet 2 evenings a week. The unheated temperature has never dropped below 8C. Our walls front and back are single skin brick our side walls are party walls with the buildings either side.

 

HTH.

 

 

[tomparryharry]

I have a suspended floor in my hallway, with a low cellar underneath, The joists are like yours, at 16" centres. With our house, I laid up the insulation fibre, and tacked into place with garden netting. The rationale being that should something like a mouse gained entry, there is nowhere for it to build a nest. 

 

I'm about to set out my shed floor, which will have joists, with the insulation underneath. My shed side panels will probably have a thick polythene vapour barrier, with 50-75mm Celotex behind. The outer wall will most probably be feather-edge to give a degree of weather proofness. 

 

Dave Bacon of this parish has some considerable experience on this subject, to which I will defer. 

 

As this time of year, now is the best time to be shed/garage building, as we move through summer. I'll suggest to the mods that we look at having a topic thread about sheds. 

 

Best wishes,

 

Ian.

[teaky]

I am not a professional builder but have done a few things on our house, all of which have Building Control completion certificates.  Some of the following information may help.

 

Small extension with a suspended floor - Treated timber battens across the underside of the joists before fitting PIR insulation between the joists.

 

Garage conversion to room plus storage space - Storage space is treated as if it were garage space which is logical since there are flammable paints and other liquids in there much like there are flammabe liquids in your car.  To comply with Building Regulations the dividing wall was two rows of engineering bricks plus DPC and on top of that a partition wall of treated timber and fire resistant plasterboard (the pink stuff).

 

Loft conversion - Above the existing plasterboard ceiling there is an air gap then strong wire mesh stapled to the joists supporting loft roll insulation beneath the 18mm treated chipboard flooring.

 

Reading through the Building Regulations Approved Documents will provide a lot of useful (up to date) information.

https://www.gov.uk/government/collections/approved-documents