plasterboard and insulation

[LSB]

Please can someone explain to me.

I'm trying to get my head around internal insulation, plasterboards, plastering, skimming and painting for walls.

I've been researching, but not getting far.

 

So, I have block walls which I need to internally insulate and then get ready for painting.

 

I've read about insulated plasterboard, but hear it's expensive.

then there is insulation with plasterboard on top.

Then, some research says you can paint straight onto plasterboard, but what about the joins, even when they are tapes, how would that ever be smooth, knowing that I'm painting not wallpapering.

The what about plastering versus skimming, is it simply that one is thicker than the other.

 

It seems to be that the more I look the more confused I become.

 

The plan for the floors and ceiling is SuperFOIL SFUF as we are very limited in height and this insulation is very thin.

 

TIA

 

[PeterW]

22 minutes ago, LSB said:

The plan for the floors and ceiling is SuperFOIL SFUF as we are very limited in height and this insulation is very thin.

You can’t use superfoil in floors - it needs airspace to work despite what the manufacturers try and tell you.  So you need to budget for a minimum of 100mm insulation there. 
 

In terms of the roof, what is the current structure and build up ..??

[LSB]

5 minutes ago, PeterW said:

You can’t use superfoil in floors - it needs airspace to work despite what the manufacturers try and tell you.  So you need to budget for a minimum of 100mm insulation there. 
 

In terms of the roof, what is the current structure and build up ..??

 

I don't think I can use the foil in the roof either, after looking, as it's a warm roof which needs much thicker insulation.
I need thin insulation for the floor which handles UFH and I thought from my research that you could use the foil, back to the drawing board.

We have a metal flat roof, well 5 degrees and we have a maximum ridge height of 3.015m.  With that pitch it takes us down to 2.276 at the lowest point with the roof 9.3m.

This is pretty low so we are planning the layout to handle this, but we need to minimise both floors and ceilings as much as possible.

Our architect made all the lowest bits storage, but that loses a lot of living space so I want to make it more usable.

 

[Dave Jones]

what is the build structure ?

[PeterW]

9 minutes ago, LSB said:

I need thin insulation for the floor which handles UFH and I thought from my research that you could use the foil, back to the drawing board.

OK so your thinnest standard insulation is PUR, Kingspan Kooltherm is a brand you may see. What is the final floor finish, and why can’t you dig the floor out ..?

[OldSpot]

Hi LSB,

 

I'd second what PeterW says about the superfoil in floors! Yep the manufacturer will tell you it can be done and granted it'll give you a bit of insulation but it won't be effective.

 

Back to your original question(s)...

Presumably you don't have an insulated cavity wall if you are considering IWI (internal Wall Insulation)?

 

You can attach plasterboard to your block wall in various different ways. The two most common are:

1. "Dot and Dab": This is where you use adhesive and put a number of lumps on the back of the board and then stick it to the wall.
2. Battens: Screw battens to the block work and then screw the plasterboard to the battens. Using this method you can more easily insulate between the battens and then also attach a layer over the top. Either as an individual layer or using insulated plasterboard. You do also need to incorporate a vapour barrier.

Alternatively, you can plaster the block work. Firstly with something like Thistle Hardwall or Thistle Bonding (depending on what the blocks are) as an undercoat and then a second (finish) coat is applied such as Thistle MultiFinish.

If you use the plasterboard method, you can tape the joints on the plasterboard (tapered edge board not square edge) you then use a jointing compound and sand it down to get it smooth. See here. Or, you can apply a skim coat of plaster. The skim coat will give you a much better finish but does cost more.

 

[LSB]

17 minutes ago, PeterW said:

OK so your thinnest standard insulation is PUR, Kingspan Kooltherm is a brand you may see. What is the final floor finish, and why can’t you dig the floor out ..?

we are doing a barn conversion so we can't dig the floor very far because of the limited foundations of the existing walls that we must keep.  We are planning on going down a bit, but that is already allowed for in the height calculations.

 

[LSB]

21 minutes ago, Dave Jones said:

what is the build structure ?

this is a barn conversion, we must keep the existing walls and roof type (metal) so are limited with what we can do.

 

[Russell griffiths]

I think you need to do a section drawing of the whole structure, so people can understand where and how to install insulation. 

You could also do a drawing or pictures of the wall build up. 

Its just not a case of slapping some insulation on your walls it’s all to do with what you have know versus what you need to achieve. 

[OldSpot]

Do the walls have a DPC?

 

[Dave Jones]

ah ok.

 

id definitely be digging down to get some height for starters. 

 

Assume you are removing all the external tin and replacing so will be able to make a cavity to fill with insulation. Are you having a blockwork inner skin or going for studwork ?

[LSB]

4 minutes ago, OldSpot said:

Hi LSB,

 

I'd second what PeterW says about the superfoil in floors! Yep the manufacturer will tell you it can be done and granted it'll give you a bit of insulation but it won't be effective.

 

Back to your original question(s)...

Presumably you don't have an insulated cavity wall if you are considering IWI (internal Wall Insulation)?

 

You can attach plasterboard to your block wall in various different ways. The two most common are:

1. "Dot and Dab": This is where you use adhesive and put a number of lumps on the back of the board and then stick it to the wall.
2. Battens: Screw battens to the block work and then screw the plasterboard to the battens. Using this method you can more easily insulate between the battens and then also attach a layer over the top. Either as an individual layer or using insulated plasterboard. You do also need to incorporate a vapour barrier.

Alternatively, you can plaster the block work. Firstly with something like Thistle Hardwall or Thistle Bonding (depending on what the blocks are) as an undercoat and then a second (finish) coat is applied such as Thistle MultiFinish.

If you use the plasterboard method, you can tape the joints on the plasterboard (tapered edge board not square edge) you then use a jointing compound and sand it down to get it smooth. See here. Or, you can apply a skim coat of plaster. The skim coat will give you a much better finish but does cost more.

 

thanks for this information

we are doing a barn conversion with single block walls which we must keep, as we must keep the roof type (metal) and pitch.

 

I'm just getting to the stage now  where I feel like I know less now that I did to start with.

 

 

[PeterW]

4 minutes ago, LSB said:

we are doing a barn conversion so we can't dig the floor very far because of the limited foundations of the existing walls that we must keep.  We are planning on going down a bit, but that is already allowed for in the height calculations.

 

Got any plans of what is existing ..?? You can step the dig out if you need to to give you more for insulation and allowances for screed etc. 

[LSB]

3 minutes ago, OldSpot said:

Do the walls have a DPC?

 

we are not sure at the moment.

there are multiple floor levels, some of which are floating floors and until we get them out we can't see.

the barn was build in the 60's so I think it will have.

 

[LSB]

2 minutes ago, PeterW said:

Got any plans of what is existing ..?? You can step the dig out if you need to to give you more for insulation and allowances for screed etc. 

we don't have any detailed plans of the current floor at the moment, getting them once our contamination surveys are done.

[Dave Jones]

As I understand you have to keep the external elements as is but not the internals. 

 

Have to keep doesn't mean you cant take them down and rebuild to housing standards as you woulkd never be able to fix anything otherwise.

 

It just must be the same when you put it back.

 

 

Edited November 13, 2020 by Dave Jones

[LSB]

1 minute ago, Dave Jones said:

As I understand you have to keep the external elements as is but not the internals. 

 

Have to keep doesnt meen you cant take them down and rebuild to housing standards

 

 

we have considered that, but at the moment the work and cost that would entail is huge.

The back wall is 24.5m long and the side ones between 10 and 16 (it is an L shape), my calculations were that it is over 5,000 blocks.

Also, the planners have told us that this is not acceptable as that would constitute a new build in the country and not a conversion.

if we did this it would have to be one wall at a time, and in fact with the long one part of it.

 

[PeterW]

1 minute ago, LSB said:

The back wall is 24.5m long and the side ones between 10 and 16 (it is an L shape), my calculations were that it is over 5,000 blocks.

50m at 3m high (ish) is 150sqm or 1500 blocks. There are 10 blocks to the square metre. 

Or are you considering double skin and rebuild of the whole lot ..?

 

[OldSpot]

Might be worth a look in the Barn Conversion section of this forum. I'm sure that others have come across many of the issues you are facing.

If you don't have a dpc, with solid walls breathability can be an issue. Having trodden a similar path to you have a read up on limecrete. I haven't used it as it wasn't readily available then but may give you another option.

[Dave Jones]

have you priced the build yet ? If you think blocks are expensive you may be in for a bit of shock!

 

Have you submitted your plans to building control ?

 

You starting with the most expenive type of build as well a conversion. 

 

You have a massive floor area 24mx16m 384m2 

 

Even if you do all the work yourself you we be very lucky to get sub £1000 m2 and your worrying about 4k's worth of conc blocks....

 

Get the whole lot priced so you know what your getting into.

 

 

Edited November 13, 2020 by Dave Jones

[A_L]

33 minutes ago, LSB said:

The back wall is 24.5m long and the side ones between 10 and 16 (it is an L shape),

 

If we can assume a floor area in the region of 317m² then 60mm of PIR (0.022W/mK) or 100mm of EPS (0.035W/mK) will give U values of 0.19 for PIR or 0.18 for EPS. U values will tend lower for larger areas.

[Nick Laslett]

What about Aerogel, very thin, might be too expensive?

https://www.thermablok.co.uk/our-products/thermablok-aerogel-magnesium-floor-board/

 

https://www.phstore.co.uk/spacetherm

Edited November 13, 2020 by Nick Laslett

[nod]

12 hours ago, LSB said:

Please can someone explain to me.

I'm trying to get my head around internal insulation, plasterboards, plastering, skimming and painting for walls.

I've been researching, but not getting far.

 

So, I have block walls which I need to internally insulate and then get ready for painting.

 

I've read about insulated plasterboard, but hear it's expensive.

then there is insulation with plasterboard on top.

Then, some research says you can paint straight onto plasterboard, but what about the joins, even when they are tapes, how would that ever be smooth, knowing that I'm painting not wallpapering.

The what about plastering versus skimming, is it simply that one is thicker than the other.

 

It seems to be that the more I look the more confused I become.

 

The plan for the floors and ceiling is SuperFOIL SFUF as we are very limited in height and this insulation is very thin.

 

TIA

 

If you are looking for high levels of insulation on solid walls 

It won’t be cheap 

I’m a plastering contractor and used insulated pp onto the block work Don’t use Parge coat it’s a waste of money and unnecessary if the room is sealed properly 

Another option Perhaps the best for you would be to add a 50 mil metal stud and insulate or add your multi foil behind it Leaving good airflow As Peter has already pointed out 

[LSB]

13 hours ago, PeterW said:

50m at 3m high (ish) is 150sqm or 1500 blocks. There are 10 blocks to the square metre. 

Or are you considering double skin and rebuild of the whole lot ..?

 

It would be the following length, 24.5 + 9.5 + 19 + 6 + 5.5 + 16 = 90.5 one skin, doubled = 181 + internal walls as they need to be load bearing which is loads, can't find my measurements to hand.  Hence the 5,000 ish count.
If you look at my blogs there is a plan in there.

[PeterW]

Ok but that means you are already including the 3 walls you need to retain ..?

 

You also need to do your opening allowances and that can remove quite a lot -  20% of floor for windows would take out 1100 from your 275sqm ish floor plan. All this needs factoring in, and it may pay you to use an online estimator to just get a ballpark of the quantities needed. 

I am not sure why your internal walls need to be load bearing either as this is a pre-existing structure that is obviously standing now ..??