Garage Conversion

[the-shack]

Hi, I'm new to DIYnot so I hope somebody can help. I'm planning to convert part of my integral garage into a room and have a few questions. I’ve fitted kitchens and bathrooms and refurbished rooms but never carried out such a large project.

1. I wish to install a new door from the hall into what will be the new room. This is an external wall with a cavity. I'm planning to use 2 concrete lintels 1200mm long but I’m unsure of the size. The wall is supporting the joists of the first floor.

2. I’m planning to infill the garage door with a windows and UPVC cladding on a timber frame below. So the frame is not on the floor I shall lay 3 courses of blue bricks on the existing garage floor. Is this OK?

3. The roof is pitched and I shall insulate using normal loft insulation. If this OK.

4. The walls of the garage are double brick without a cavity. I’m planning to batten this out with 50mm battens and infill with 50mm kingspan, then cover with foil backed plasterboard. Where the garage door was I shall double the insulation. As I’m only converting part of the garage into a room I shall be fitting a stud partition about 2/3 down the garage so the end can be used as a store.

5. Finally I plan to install a suspended wooden floor using 50x97 SC3 timber supported mid length. (Approx 1190mm span) 400mm apart and in filled with 50mm kingspan and cover with 18mm chipboard flooring. Ventalation will be provided by air bricks installed in the door infill.

Am I close to doing this correctly or way off the mark?

 

[noseall]

[quote="the-shack";p="1109658"1.

I wish to install a new door from the hall into what will be the new room. This is an external wall with a cavity. I'm planning to use 2 concrete lintels 1200mm long but I’m unsure of the size. The wall is supporting the joists of the first floor.

sounds good so far.

2. I’m planning to infill the garage door with a windows and UPVC cladding on a timber frame below. So the frame is not on the floor I shall lay 3 courses of blue bricks on the existing garage floor. Is this OK?

even though there is insubstantial weight going on the slab, it still may not be adequate, or you may need to prove the slab is strong enough to deal with the load.

3. The roof is pitched and I shall insulate using normal loft insulation. If this OK.

yep, sounds good. you will need a minimum of 250mm insulation plus ventilation.

4. walls of the garage are double brick without a cavity. I’m planning to batten this out with 50mm battens and infill with 50mm kingspan, then cover with foil backed plasterboard. Where the garage door was I shall double the insulation. As I’m only converting part of the garage into a room I shall be fitting a stud partition about 2/3 down the garage so the end can be used as a store.

the 9" solid walls will require a continuous insulation sheet across the battens and not between them. the timber stud partition wall can be filled with 100mm kingspan plus a 25mm layer across the studs.

5. Finally I plan to install a suspended wooden floor using 50x97 SC3 timber supported mid length. (Approx 1190mm span) 400mm apart and in filled with 50mm kingspan and cover with 18mm chipboard flooring. Ventalation will be provided by air bricks installed in the door infill.

you will need to use 75mm insulation boards under the floor and if solid filled, no need for vent's.

 

[the-shack]

Hi noseall, thanks for responding and i'm sorry for not getting back eairler been a bit busy at work.

Thanks for your advise but I have some more question.

You did not say what size lintel to use. Wickes sell 100x70x1200 would these be OK?

For the walls would I be better to use 62mm insulated plasterboard fixed to battens on the wall. If so what would be the minimum thickness of battens I should use and would I need a damp proof membrane?

I'm also assuming that the wall adjoining the house will not require any insulation (Filled cavity wall).

Finally down one wall (the cavity one) I have a gas pipe. Can this be hidden behind plaster board or should I have it moved?

Thanks again for any help.

Cheers

 

[noseall]

100 x 75mm (1200mm long) pcc lintels are, in most cases, ok.

Use 50 x 25mm tanalised lathe for battens spaced at 400mm centres.

No need for vapour control if you use foil backed insulation.

No need for additional insulation on a full spec' cavity wall.

 

[the-shack]

Had to take a break from the conversion but it's all go. I have had the BCO officer around and he has OK'ed the bricking up of the door without new foundations. I have had a builder round to do this and the window went in a week ago so I'm all weather proof now. The insulation comes tomorrow so looks like I'm having a busy weekend.

I have decided to use 100mm Jablite followed with 75mm Celotex and a layer of 22mm Chipboard for the flooring which will take me up to the same level as the existing floor (give or take a couple of mm). This method was advised by the BCO.

The walls are being insulated with 50mm Celotex fixed to the wall with 25x50 batterns (screwed through) then the whole thing will be covered in 12.5mm plasterboard. According to Celotex this will give me a U value of .35W/m2K, enough to satisfy the BCO. This also gives me a gap to run the services. (heating/electrics etc)

I have another question. Do I use tanalised sawn timber for the batterns or would it be better to use kiln dried?

Below are some pictures of the work so far. You can see the new door into the hall and the front wall before the window went in. You can also see the garage door behind the new wall. I moved it back a couple of feet to allow the builder to do his stuff and keep the garage secure.

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• the-shack
• 11 Oct 2009
• 1

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• the-shack
• 11 Oct 2009
• 1

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• the-shack
• 11 Oct 2009
• 1

I'll post some more pictures when I have downloaded them from the camera.