plasterboard and insulation

[LSB]

I'm currently looking at our options for the internal part of our conversion.

I'm not very knowledgeable about the best way to do some things.

 

We have a single skin blockwork barn that we are converting, the outside will be EWI (yes we do have permission), but I'm wondering about inside.

We are planning on putting plasterboard inside om a DIY basis, but I'm wondering what is the best way.

Should we put battens and then screw in the boards, or dot & dab onto the blocks or screw to the blocks, can we use nails rather than screws using the nail gun.

If we use battens should we put some insulation in the batten spaces.

How do we stop cold getting in if we use screws.

Should we tape each board edge.

 

The wall will be skimmed before decorating.

 

Is there a different process for wet rooms.

 

Most articles I read suggest dot & dab, but as we are trying to follow a fabric first approach and insulate the house as much as possible, as it won't have a cavity.

We are planning ASHP & UFH & MVHR, does this make a difference.

Most of the internal walls are staying and are block although we will be building a few stud walls for things like wardrobes.

 

TIA

 

[Dudda]

What is the single skin made of? As you're converting an old barn its not clear the age of the building and if its modern blockwork or an old solid stone or brick wall? Does this wall have lime mortar or concrete and does it have a DPC?

 

I'm asking as this is important to determine the build-up. If stone with lime mortar the wall will need to breath on both the internal and external layers and will need a vapour control layer. If modern blockwork you'll have more options.

[LSB]

2 minutes ago, Dudda said:

What is the single skin made of? As you're converting an old barn its not clear the age of the building and if its modern blockwork or an old solid stone or brick wall? Does this wall have lime mortar or concrete and does it have a DPC?

 

I'm asking as this is important to determine the build-up. If stone with lime mortar the wall will need to breath on both the internal and external layers and will need a vapour control layer. If modern blockwork you'll have more options.

It's a modern barn build from blockwork.

 

[Dudda]

Personally I'd put external insulation (as much as you can afford but aim for 200mm. Internally I'd plaster the blockwork with a wet parge coat after the windows are inserted and have had the airtight tape fitted. This parge coat will be the airtight layer of the house. Then I'd put in timber battens at 600mm centers fixed with concrete screws to the walls. This will form a void where you can run the electrical cables and create a recess for electrical back boxes. Then plasterboard is fixed to the timber battens. As it's an old barn the internal timber battens will allow you to make the walls plumb or take out any issues but to be fair they look decent enough from the photo.

[LSB]

2 minutes ago, Dudda said:

Personally I'd put external insulation (as much as you can afford but aim for 200mm. Internally I'd plaster the blockwork with a wet parge coat after the windows are inserted and have had the airtight tape fitted. This parge coat will be the airtight layer of the house. Then I'd put in timber battens at 600mm centers fixed with concrete screws to the walls. This will form a void where you can run the electrical cables and create a recess for electrical back boxes. Then plasterboard is fixed to the timber battens. As it's an old barn the internal timber battens will allow you to make the walls plumb or take out any issues but to be fair they look decent enough from the photo.

Thanks, we have EWI planned, but as I've started stripping the barn (this is the only shed I've done so far) I need to plan for the rebuild even though it won't be for some time.

The walls are not too bad and we are lucky that it's not particularly damp.  

How thick is a parge coat ?

The void is crucial as I'm planning on lots of cables for electricity & network etc.

 

[Dudda]

1 minute ago, LSB said:

Thanks, we have EWI planned, but as I've started stripping the barn (this is the only shed I've done so far) I need to plan for the rebuild even though it won't be for some time.

The walls are not too bad and we are lucky that it's not particularly damp.  

How thick is a parge coat ?

The void is crucial as I'm planning on lots of cables for electricity & network etc.

 

Parge coat is about 5mm. It's just a thin layer of very wet cement put on like a thick coat of paint. It's something very doable yourself as it won't be seen.

 

The internal batten size is up to you. You can go with 25mm, 35mm or even 50mm battens if you want a large void. The larger could incorporate additional insulation if required particularly at the floor as this will help with thermal bridge with cold coming up through the existing wall from the earth. On new builds lightweight thermal blocks are used to stop this but it's not possible to insert these in you're case.

 

What are you doing to the existing floor? Are you retaining it or how are you insulating?

[TonyT]

Electrical metal boxes come in 25,35 and 47mm deep.

 

personally I think 25mm are too shallow and if you have flat plate accessories they won’t work.

 

35mm boxes are ideal for everything electrical apart from cooker, shower switches as the cable is thicker and 47mm. Gives more room to terminate.

 

data cabling needs some room to terminate with the bending radius to be considered cat 6 cables need 47mm boxes.

 

( but 35mm batten plus 12.5 plasterboard will let a 47mm box be fitted )

 

you get plastic fast fix boxes but .......

[ProDave]

1 hour ago, TonyT said:

you get plastic fast fix boxes but .......

No problem if you use Appleby.  Agreed some other makes are utter rubbish and not fit for purpose.

A 35mm back box is perfect for a 25mm service void and 12.5mm plasterboard.

[LSB]

2 hours ago, Dudda said:

Parge coat is about 5mm. It's just a thin layer of very wet cement put on like a thick coat of paint. It's something very doable yourself as it won't be seen.

 

The internal batten size is up to you. You can go with 25mm, 35mm or even 50mm battens if you want a large void. The larger could incorporate additional insulation if required particularly at the floor as this will help with thermal bridge with cold coming up through the existing wall from the earth. On new builds lightweight thermal blocks are used to stop this but it's not possible to insert these in you're case.

 

What are you doing to the existing floor? Are you retaining it or how are you insulating?

We are digging the existing floor out (well some of it) as it is currently on 4 different levels with the top 3 being floating floors not even actually touching the walls, I want level access everywhere ready for my wheelchair.

Then we are going to put in a new slab, insulation, UFH and screed and within that a DPM, we are also allowed to add an additional block to the wall height at the black, the part in the picture.  Currently the roof is two different levels, we can't increase the top ridge, but this part is 704mm lower, we need to keep the pitch for the zinc (metal) roof, but one block at least gives us something.  This also allows us to add a lintel over the window.  That is one restriction we have, either use the existing openings or hide them, but we can't have new ones.  I wanted a window on the left hand wall looking down the hill, but that isn't allowed.

If you look in the picture you will see that you can only see half of the block at the bottom, so we are going down to expose all of it.

We don't have very deep foundations, but they are good enough for this according to our SE.