Walls- what can be used?

[zoothorn]

Hi- I have a very simple proposed small extention. Upstairs room (an extention of house, a bedroom/study), over a workshop below. 4x5m floor area.

 

I have a tight budget (doing the 'easier' build stuff myself) but need solidity too- weather pummels the spot. So far I have successfully got PP.

 

Q: If I rule out block > cavity > brick, due to budget.. what are my options of wall construction? (waddle & daub ruled out too!). I understand one option is timber frame > cladding, but the 'cavity' part I'm confused if regs stipulate a fixed size, or if a cavity isn't compulsory (with any wall?). And no. of courses etc.

 

thanks zoot.

 

 

 

[Carrerahill]

I don't think you should rule out block, I have just done my TF for my extension and to be honest, it would have been cheaper to do it in block knowing what my brickie charges and the material cost - I did mine in TF as it let me do it myself (I can lay block but not fast and if it is not perfect I get annoyed and pull it down) - I can carry on inside and the block will go up mid June. 

 

Remember with TF you have your sticks in various sizes and sistered up for cripples and lintels and things so you burn through lots of timber, then it's fully sheeted in OSB then you have membrane, then your timber firestops/door-window aperture surrounds, then you have the time it takes to build the TF and the materials to build it (1000's of nails) then rolls of DPC for sill plates and all sorts - tie downs, TF tie's, you name it. For block you are about £20 square meter. That's about £10 in materials (block, sand, cement) and a £1 a block laid.

 

 

 

 

[ToughButterCup]

ICF? 

Its not the answer to every problem, specially not if you lay them in the nude.?

[scottishjohn]

If current house is block --then i would be thinking the same cavity block is a good choice ,especially as you are having a garage --+ workshop under it

 block walls are easy good for fixing things too ,and you could could just paint them in garage ?

any system will do it ,but  I doubt there is  one that is half the price of the other ones.

small extension ,then maybe ICF and hand mix the concrete if you time and want to save money -can,t lay blocks ,

or maybe look at thin joint block system --easier for novice to lay good walls p-roviding first row is right .

I,m  not pushing any type --do some homework 

[scottishjohn]

4 minutes ago, AnonymousBosch said:

ICF? 

Its not the answer to every problem, specially not if you lay them in the nude.?

It is if you can charlie theron to lay them 

If ICF  

check out durisol +Isotex

Edited May 30, 2019 by scottishjohn

[zoothorn]

Thanks chaps. My house is an old miner's cottage, 3ft thick slate, side wall to build onto is an uneven/ 'contoured' typical stone surface.

 

What I'm trying to understand, is the 'layers' of different options, & what I have to do to meet regulations regarding my wall construction.

 

For eg, would I be allowed to go simply one block course / roof ontop (ceiling joists separating the two rooms via metal ties between walls).. lining inside walls with battens > insulate > plasterboard.. for either room, or even both?

[PeterW]

19 minutes ago, zoothorn said:

For eg, would I be allowed to go simply one block course / roof ontop (ceiling joists separating the two rooms via metal ties between walls).. lining inside walls with battens > insulate > plasterboard.. for either room, or even both?

 

No

 

If you go with block then you need to go (inside to outside)

 

Plasterboard

Block

Cavity (with Insulation)

Block

Render

 

This will give you a wall of 325mm thick, there or thereabouts. 

 

Floor joists will go on the inside skin, both block skins connected by ties.

 

Roof (if you want a full open apex) will be hung on a ridge beam / steel resting on inside skin.

 

As @Carrerahill says, I recon £20/m for blockwork is about right so that would give you around 150sqm of block and a £3k bill for that section. TF would probably come out not dissimilar I would expect

[zoothorn]

Ok Peter- many thanks for that. Did I get it wrong then, that the outer course of your wall above, instead could be timber of some sort.. or something other than block-? 2 block courses seems way overkill for my workshop, if not the small room above too.

 

I was thinking recently along the lines of (in terms of solidity, & what I might be able to afford, & right approach for the design).. inner course block > cavity (if I have to) > outer vertical wood cladding (those ~4" strips, in-out-in etc). Is this not allowed then?

[PeterW]

23 minutes ago, zoothorn said:

Ok Peter- many thanks for that. Did I get it wrong then, that the outer course of your wall above, instead could be timber of some sort.. or something other than block-? 2 block courses seems way overkill for my workshop, if not the small room above too.

 

I was thinking recently along the lines of (in terms of solidity, & what I might be able to afford, & right approach for the design).. inner course block > cavity (if I have to) > outer vertical wood cladding (those ~4" strips, in-out-in etc). Is this not allowed then?

 

You have planning for a rendered outside wall finish, which you have permission to build. If you change it to vertical wood cladding then you will have to go back to planning for a new approval.

 

In your example you have no insulation - where are you putting this as you have to have it...?

[Declan52]

You can build a single skin block but it will be a standard 4 inch block on its flat so you will end up using the same amount as you would with a cavity. Plus as you will have no cavity to help keep the rain from getting into the inside you have to use a certified waterproof system to plaster and seal the wall up. With a cavity you can just use a sand cement mix and rub it up and leave it. Let it sit a few years then fill any cracks and paint it whatever colour you like or just leave it grey.

With a single skin then all the insulation will be on the inside so isn't as easy to put in place compared to a cavity. 

You need 10 standard blocks for each sqm. So work out how many sqm you have then X 10. This will give you how many you need so you can phone round and get a price. Once you know how many blocks then you can work out how much motar you need. A bag of cement and 3 sand will build about 30-35 blocks depending on how much you drop.

It's time to be realistic. Can you build block or can you get some one who will but won't charge you plenty. It would be my preferred option as , being realistic time again, do you think you can make a set of timber frame panels up that will be to the right size and shape and square.

[Russell griffiths]

What sort of budget do you have. 

 

That way we can tell you if it’s a complete non starter. 

 

 

[PeterW]

11 minutes ago, Russell griffiths said:

What sort of budget do you have. 

 

That way we can tell you if it’s a complete non starter. 

 

 

 

£30k - it’s on the other thread 

[zoothorn]

1 hour ago, PeterW said:

 

You have planning for a rendered outside wall finish, which you have permission to build. If you change it to vertical wood cladding then you will have to go back to planning for a new approval.

 

In your example you have no insulation - where are you putting this as you have to have it...?

 

It sounds like I'll have to go back anyway, if my top room wasn't 'open'? ok so now I know I have to have insulation: I didn't know this was compulsory. Is anything else compulsory within the wall structure? I had no idea the PP was for a wall method already chosen: I thought the  wall method choosing came after PP, but before I get quotes. You see how impossible this process is for me/ anyone to understand how to progress? there are simply no guidelines.

 

As to where would I be putting this insulation in my eg, I don't know: all I know is I see builds with this vertical cladding. If there's a separate, inner course (?) & this is the outer course, & its compulsory to have insulation- then the eg's I see MUST have insulation. So to answer your Q: "wherever that one's insulation is/ however that was done". I thought it might be a usual wall type I could be told of.

 

Options so far I think are: block/ block, TF (which seems to be timber + block, or timber + timber.. or is it.. I'm confused by TF), ICF which I've never seen & don't see on builds anywhere here, & my vertical-clad eg.. which I don't know how is done so unknown if an option I can choose.

 

 

[PeterW]

No

 

Planning give you approval to build what it looks like on the outside

 

Building control give you approval to build it to the correct regulations 

 

The building regulations tell you stuff such as structure, windows and doors, foundations, electrics, drainage, insulation and those things. 

[Declan52]

No matter what you build it will have to be to the building regs so will have to have some quantity of insulation.

With block the easiest is in the cavity and the easiest and best method is to get it blown in. 

With timber frame the insulation is in between the studs. This can be pir cut to suit, Rockwool  or you can get different types sprayed in. Your choice on the type but it has to meet the regs. 

With timber frame your going to need something to keep the rain out. You can build a skin of block or use something like a cement board and then plaster this up. Once again your choice. 

You can go for cladding but your permission is for render finish so unless you go back to them and reapply then you have to stick with what they have passed.

[zoothorn]

Understood Peter. But if these two will look the same on the outside A) a block course + render.. & B) a wood course + "render board" then have I got PP for "any sort of rendered outside regardless of what material is behind the outer rendered layer"?

[zoothorn]

Forgetting my particular PP for the moment: it seems I'd no idea the finish was decided at this stage: I thought PP was -only- to do with the size, shape, & location of the extention. I thought then the finish specs a building regs thing IE once PP got I had a choice of wall & finish methods to then choose > then I go to a builder for a quote. Looks like Ive done the whole thing backwards.

 

So I might have to go back to PP. But, if I had to anyway due to opening up the top room ceiling (?) & these vertical clad things look good if not better than boring smooth render.. I can't see a problem. Non-material ammendment is it? I might add a foot to overall length anyway as I'm there.

 

In terms of construction only, could I have a block inner course + cavity/ insulation, then something -other- than block or brick as my outer course? this vertical wood cladding for eg? if Timber Frame Co's say "the outer course.. world's your oyster/ up to you entirely you can have xyz"

[Carrerahill]

30 minutes ago, zoothorn said:

Understood Peter. But if these two will look the same on the outside A) a block course + render.. & B) a wood course + "render board" then have I got PP for "any sort of rendered outside regardless of what material is behind the outer rendered layer"?

PP is what it will look like and the impact it will have on the surrounding area, PP really only concerns themselves with the external appearance - that is PP in a nutshell. Alongside PP you also need your approved construction detail which will be approved by BC - they want to know how you are going to build it right down to the size and type of nail you will use to nail the ceiling joist to the wall plate - I am not kidding!

 

What BC expect is a set of relevant drawings and details showing how you will build your building - you can't just say - "I will build a render finished building" and build it however you choose - it's really there to ensure buildings are built properly and with good thermal values, fire safety etc. It may also impact the rest of your house, in my case I need to add smoke alarms to other rooms and a fire escape window to the old kitchen. 

 

So for my extension there is a fairly simple drawing showing the extension and make up of the wall in plan, where windows and doors will go, where pipes, electrical will go, where fire-stops will go, etc. Then there is a standard wall detail which is a written section that basically says: "19mm render on 100mm block with 50mm cavity then reflective breathable membrane onto 12mm OSB on 125x45mm studs @ 600mm centres, insulated between with 100mm PIR then plaster-boarded with foil backed 12.5mm PB." There was also a typical TF wall detail drawn which shows window opening/lintel details etc. 

 

So you need to work out a wall construction, then detail it and that is what BC will approve (or not). 

 

 

 

 

 

 

Edited May 30, 2019 by Carrerahill

[Carrerahill]

11 minutes ago, zoothorn said:

Forgetting my particular PP for the moment: it seems I'd no idea the finish was decided at this stage: I thought PP was -only- to do with the size, shape, & location of the extention. I thought then the finish specs a building regs thing IE once PP got I had a choice of wall & finish methods to then choose > then I go to a builder for a quote. Looks like Ive done the whole thing backwards.

 

So I might have to go back to PP. But, if I had to anyway due to opening up the top room ceiling (?) & these vertical clad things look good if not better than boring smooth render.. I can't see a problem. Non-material amendment is it? I might add a foot to overall length anyway as I'm there.

 

In terms of construction only, could I have a block inner course + cavity/ insulation, then something -other- than block or brick as my outer course? this vertical wood cladding for eg? if Timber Frame Co's say "the outer course.. world's your oyster/ up to you entirely you can have xyz"

 

I did PP and BW applications simultaneously for speed - we were certain PP would be fine with it so were happy that changes would not be needed and in the end PP and BC arrived almost the same day. 

 

As said in my post just above this one, but written after the post I am now replying to, PP want to know how the thing will look, that includes finishes. Renders and woods and tiles and slates and downpipes etc.

 

So you have PP? If so what does it detail for the buildings finished look? Render is it? So now you just need to pick an acceptable wall construction that is finished in render and apply to BC to for approval 

 

 

Edited May 30, 2019 by Carrerahill

[zoothorn]

Hi Carrerahill-  I understand what you say, apply for PP > then for BR. I have to establish 1st if I need to do this (may be different in wales, or, I may have done some BR thing already 'in with the PP' application.. as someone has hinted maybe might be so in my case).

 

So I need to call the BCO I think to find out what's what as I'm totally lost.

 

Then if its needed, I need to establish who makes this application (me, builder, my 'architectural consultant'.. is this what I'm paying him £1.5k for??) & then what it entails.

 

 

 

Edited May 30, 2019 by zoothorn

[PeterW]

You have PP

 

You still need to apply for BRegs

 

Ignore the receptionist as they are wrong ..!! 

[zoothorn]

14 hours ago, PeterW said:

You have PP

 

You still need to apply for BRegs

 

Ignore the receptionist as they are wrong ..!! 

 

Called my BCO, for clarity & says as you did PeterW. I'm separating walls info for here, & PP & BRegs/ general extention onto other thread https://forum.buildhub.org.uk/topic/9742-zoots-extension-advice-needed/?page=3&tab=comments#comment-167863

 

thanks.

 

 

 

[zoothorn]

So getting back to walls, could I go inner course block / outer course (vertical wood-clad) something or other?

[PeterW]

1 hour ago, zoothorn said:

So getting back to walls, could I go inner course block / outer course (vertical wood-clad) something or other?

 

No

 

you have no insulation in that plus I’m not sure you could use wood as a flammable wall cladding that close to the road without coating it but would need to check. 

 

To use timber  cladding and block you would need (from the inside)

 

plasterboard

block

cavity with insulation

block

batten

cladding

 

I recon you should stick with block and render and a cut roof, steel supporting the roof timbers, unless you want to go the full timber frame deal with a render board finish. 

 

[Russell griffiths]

1 hour ago, zoothorn said:

So getting back to walls, could I go inner course block / outer course (vertical wood-clad) something or other?

 

Nope, 

not unless you go 150mm blocks

how will you hold the second storey up, you can’t go two storey in a single skin of blocks, it would just not stand up.