New Kitchen/Living extension. Brick & block or brick and timber?

[PeterW]

  On 16/11/2018 at 21:23, Triggaaar said:

Thanks. So having your 25mm of PIR was more expensive than another 25mm of cavity and beads, but it was worth it for the better uValue and ease of running cables. All sounds good. I'll suggest the architect puts this in the plans.

Would I need a specialist to fill the cavity with beads? Presumably they drill holes in the finished blockwork, and once they're done I can install the PIR?

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Correct on all counts ..! Beads are blown in using a special machine and they did 15 cubic metres in less than 3 hours. The beads are blown in and coated in a film of glue that sets and keeps them from moving in the wall. 

[Triggaaar]

If I go with this design, the finished walls will be about 15.5". One wall is a completely new wall, so that's fine - the other wall will be joining an existing Edwardian cavity wall, which is about 11 or 12" wide. Is it ok to add PIR (maybe 75mm) to the inside of the existing wall, or will that cause problems?

[Ferdinand]

  On 13/11/2018 at 18:01, Triggaaar said:

There would only be a 50mm cavity between the bricks and the Tyvek/ply/studs, which means we'd need to build the stud wall first, then put 600mm strips of ply in place (with rolls of Tyvek in the way), then reach over to lay the bricks and add ties, before doing the next strip of ply. Meaning just 6" space between the ply and the existing brick boundary wall, to get fixings in (from ply to timber stud).

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That proposal to build overhand concerns me.

 

AFAIK it reduces the visual quality of the work substantially, especially if you have to make like Mr Tickle to build it. 

 

Can you maintain it, and will you neighbour have to look at it? 

 

For me, negotiating access would be a better option for appearance and relationships, or even better leaving enough room so you can get to the outside of it.

 

Ferdinand

 

Edited November 17, 2018 by Ferdinand

[Triggaaar]

  On 17/11/2018 at 06:48, Ferdinand said:

 

That proposal to build overhand concerns me.

 

AFAIK it reduces the visual quality of the work substantially, especially if you have to make like Mr Tickle to build it. 

 

Can you maintain it, and will you neighbour have to look at it? 

 

For me, negotiating access would be a better option for appearance and relationships

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We're talking about where the wall butts up against the boundary wall, so no one would be able to see it. Once the wall went above the boundary wall, the brickie would go to the neighbours side to build.

 

Although the opinion here seems to be that we're better using brick and block anyway.

 

[PeterW]

  On 17/11/2018 at 10:12, Triggaaar said:

 

We're talking about where the wall butts up against the boundary wall, so no one would be able to see it. Once the wall went above the boundary wall, the brickie would go to the neighbours side to build.

 

Although the opinion here seems to be that we're better using brick and block anyway.

 

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So how are you planning on doing the founds for this as if you are right up the boundary wall (yours I assume ..?) then the founds for the new wall will have to go beneath this. Would be better off dropping the wall and using the new house extension wall as the boundary by the sounds of it. 

[Triggaaar]

  On 17/11/2018 at 10:15, PeterW said:

 

So how are you planning on doing the founds for this as if you are right up the boundary wall (yours I assume ..?) then the founds for the new wall will have to go beneath this. Would be better off dropping the wall and using the new house extension wall as the boundary by the sounds of it. 

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I expect the boundary wall is shared. Our house is the boundary as far back as our house goes, and then the 9" ish wide boundary wall starts, and that wall is half on each side.

 

I haven't asked the neighbours about knocking it down. It's a nice old wall, I don't suppose they'd want it gone, and for half the run of my extension the boundary wall is the back wall of their potting shed, so they won't want me knocking that bit down. Without the potting shed issue, it would make some sense, as the boundary could be a simple continuation of our house.

 

Assuming we leave the wall, the plan is to dig 1m lengths of foundation (hopefully not too deep), put some steel continuation bars in, and fill them one at a time.

[PeterW]

Party wall agreement springs to mind here ..! If that wall is in good nick, why not get the SE to check it’s foundations and then use it as the back wall and then just build off the top of it..??

 

photo may help here ..!

[Triggaaar]

  On 17/11/2018 at 10:35, PeterW said:

Party wall agreement springs to mind here ..!

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Yes, there will be one. Hopefully they'll just sign and leave it to me, as I can't afford to pay for a surveyor for them.

 

  On 17/11/2018 at 10:35, PeterW said:

Party wall agreement springs to mind here ..! If that wall is in good nick, why not get the SE to check it’s foundations and then use it as the back wall and then just build off the top of it..??

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Lol, I wish. It's a nice old wall, not a good old wall   It won't have good foundations (might not have any at all) - it already leans and has cracks in it. It's just that it's over 100 years old, is a nice red colour and has character. As a garden wall, I like it.

 

  On 17/11/2018 at 10:35, PeterW said:

photo may help here ..!

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If needed, I'll do that. But we definitely can't build off of it. Knocking it down (for the length of the extension) would be good for us, I guess I should at least ask the neighbours

 

 

[Triggaaar]

  On 17/11/2018 at 10:35, PeterW said:

photo may help here ..!

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Ok, photos attached

One just giving a general view of the wall, the other showing how it attaches to our house. The window (edge) to the right of the join will be inside our new room).

[Triggaaar]

Hi all

 

Well we applied for planning last November, and got rejected. Fortunately we've just won on appeal, so I'm getting the building regs drawings prepared.

 

I'd like to know more about Graphite blown bead insulation, or EPS bonded beads (are they identical?):

What are peoples good and bad experiences?

Can anyone recommend a company to install them? (I'm in Brighton, if it makes a difference)

 

Thanks :)

[PeterW]

Graphite EPS has a slightly better uValue to ordinary EPS bead. Both are blown and bonded as there is a glue sprayed onto them as they are installed. 

[Triggaaar]

  On 18/07/2019 at 16:53, PeterW said:

Graphite EPS has a slightly better uValue to ordinary EPS bead. Both are blown and bonded as there is a glue sprayed onto them as they are installed. 

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Thank you!

 

The builders who have looked at the job so far don't have experience with this method, and I don't think my building regs guy does either. Should the cavity wall just be built as standard (obvs without insulation)? And do the beads then fill all the way to the foundations, past the DPC?

 

It sounds like the best option for us, but I am concerned that none of us here have any experience with it. Are they any installers you could recommend?

[PeterW]

It needs to be slightly wider for better performance - go with 150mm cavity. And yes, clear cavity, use proper cavity closers on the openings and then it’s pumped in through 25mm holes. 

 

Can’t recommend anyone down there to do it, sorry 

[Triggaaar]

  On 18/07/2019 at 18:43, PeterW said:

It needs to be slightly wider for better performance - go with 150mm cavity. And yes, clear cavity, use proper cavity closers on the openings and then it’s pumped in through 25mm holes. 

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So the beads do just go all the way down to the foundations?

[Triggaaar]

Well the build has started. I've finished the foundations, and the blocks and bricks start on Thursday.

 

Without a recommended company for the blown beads, we just decided to go for full fill cavities with glass mineral wool. 150mm on one wall, 100mm on the other, with PIR on the inside. The inner blocks are Celcon, with a thermal conductivity of 0.15W/mK. I know some go for more thermal mass inside, with more insulation outside, but the Celcons are what my building regs guy specked, and it should make the room heat more quickly from cold.

 

The plan is to have a concrete oversite (on top of hardcore) and then 100mm of PIR rated at 0.022W/mK, and a warm roof with 140mm of the same PIR. Do those thicknesses sound alright? I know we'll meet building regs, but I don't know if it's worth doing any more.

 

Re the cavities, do you think it'll make much difference whether the 100mm cavity wall insulation is 0.036W/mK or 0.032W/mK?

Since the insulation is thinner than the opposite wall, I wondered whether it would be worth putting a slightly better insulation in. It's not much more expensive, but then the difference might be so negligible it's still not worth it.

 

Thanks

[Triggaaar]

  On 16/11/2018 at 21:17, PeterW said:

25mm fits perfectly between standard roofing battens which were fitted to the walls at 400mm centres and the insulation cut to be a push fit. If you go to 50mm then you will need double the timber thickness plus the insulation will be more expensive.  

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Hi Peter

 

One of my builders suggested I use 25mm PIR bonded to plasterboard, and dot & dab it onto our lightweight blocks, instead of fitting the PIR between battens. That way there won't be thermal breaks in the PIR. Why have you gone for battens instead of the method he suggested?

 

Thanks

[PeterW]

  On 08/12/2019 at 14:36, Triggaaar said:

Why have you gone for battens instead of the method he suggested?

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Because I don’t like the idea of the shear strength of the foam being the only thing holding board and foam on, and the PIR backed plasterboard is 25% more expensive than the two products combined. That’s a lot to pay for gaining a little easier fixing. 
 

If you go that route then I’d consider the foam bonding rather than dot and dab - it stops the big gaps up the backs of the boards. 

[Triggaaar]

  On 08/12/2019 at 14:54, PeterW said:

Because I don’t like the idea of the shear strength of the foam being the only thing holding board and foam on, and the PIR backed plasterboard is 25% more expensive than the two products combined. That’s a lot to pay for gaining a little easier fixing. 

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Thank you. I'll start by getting a price comparison from my suppliers. If it is 25% more, then I'll definitely go for separates.

 

  On 08/12/2019 at 14:54, PeterW said:

If you go that route then I’d consider the foam bonding rather than dot and dab - it stops the big gaps up the backs of the boards. 

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Sorry, I don't know what foam bonding is?

 

[PeterW]

  On 08/12/2019 at 20:57, Triggaaar said:

Sorry, I don't know what foam bonding is?

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This stuff DryFix

 

 

[Triggaaar]

  On 08/12/2019 at 21:02, PeterW said:

This stuff DryFix

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Cool, thank you. I'll assume that can go between lightweight block and the PIR that the plasterboard is stuck to.

 

Edited December 9, 2019 by Triggaaar

[PeterW]

Yep - anywhere you would use adhesive 

[bassanclan]

If you are using foam bonding for insulated plasterboard (or making your own) you are supposed to fix it with additional mechanical fixings too. E.g frame fixings