# A question of construction and materials.



## Lazurus (14 Nov 2020)

I am in the position of having a purpose-built workshop for the first time in my life, this is just prior to retirement. I am looking at a 10m x 5m workshop in our back garden (subject to planning) It is currently in the design and application process. Initially I was going for a traditional double skin brick construction with insulation in keeping with the garage and bungalow – however I like the idea of a more modern looking dark grey cladding. The attached drawing shows the preliminary design. I am looking for low maintenance and, in the future, when I can no longer use a workshop converting the inside to an annex or sun room. So, I intend to put water and drainage utilities in at the point of build ready for future change of use. Can I ask advice on the best construction method and what is required in structural design to use exterior cladding, and, which type would be best?


----------



## Cabinetman (14 Nov 2020)

Wow, who is a very lucky boy Lazarus! 
Sorry I can’t help with the technical stuff except to say whatever level of insulation you are told, I would recommend you add a whole lot more, a bit more expensive now will pay off hugely in the future. Ian


----------



## Jameshow (14 Nov 2020)

I'd go for a simple 4x2 frame on 2ft centres 4" OSB / ply each side rockwood polystyrene or celotex insulation. 

You want a slope on the flat roof. EPDM rubber / fibreglass roofs are good. But more expensive than felt. 

Cheers James


----------



## spb (14 Nov 2020)

I can't say too much about construction methods, but do bear in mind that at that size you'll fall under building regulations as well as planning. Most of the advice you'll find on here is for smaller builds that don't have to comply, so just be careful on that front.


----------



## Sheptonphil (14 Nov 2020)

sounds a very exciting project.

Save yourself a whole lot of heartache for later by doing things wrong on a build like this, by employing a professional architect right from the get go. They will be conversant with local bylaws and what local authorities deem acceptable. They could save more than their cost by getting it right first time. Building control will be involved before you cut the first turf, you need to keep them on side. Construction methods on a dwelling of this size and for future habitable occupation will be vastly different to our standard workshop builds.

I’d be very wary of taking any advise from any forum except as a brainstorming excercise for ideas to pass through your architect.


----------



## Lazurus (15 Nov 2020)

I have gone an architect working on this for me as rightly said it is not a small project. Initially I was going for a standard brick build but looking at some of the newer composite claddings available I like the idea of this as a finish. I just want to be sure that the route I steer the architect down is feesible and future proof. Many thanks for the input so far.


----------



## DBT85 (15 Nov 2020)

The Hardiboard @Sheptonphil used would probably sort you for cladding purposes. Just bang it up, no need to paint it or maintain it.


----------



## HOJ (15 Nov 2020)

Sheptonphil said:


> Construction methods on a dwelling of this size and for future habitable occupation will be vastly different to our standard workshop builds.
> 
> I’d be very wary of taking any advise from any forum except as a brainstorming excercise for ideas to pass through your architect.



The big question at this stage is what it will ultimately be used for, construction methods for "residential" use as Sheptonphil has outlined, will be a totally different ball game, and consequently a far higher M2 cost, Building regs will also need SAP & "U" value calcs, possibly along with Engineers input, and if close to a Broad a Flood risk assessment along with a Landscape Character Assessment.

I have to say if I had the opportunity to build I would go residential, designing for a layout and provisioning for facilities now, in the long run you could potentially generate a tidy income from a holiday let or Air B & B, especially being on the Broads.

I have built a few "Annexes" using timber frame methods and have used both cement and timber cladding solutions, dependent on the "local vernacular" style, and how the planners have directed us, more so with the Broads Authority, they also offer free pre-application advice, which is worth using before you get too far with 
a full design drawn up.


----------



## Sheptonphil (15 Nov 2020)

DBT85 said:


> The Hardiboard @Sheptonphil used would probably sort you for cladding purposes. Just bang it up, no need to paint it or maintain it.


The cladding I used, in my case for compliance with ‘predominantly non combustible’ clause, was HardiPlank, a cement fibre board cladding system that as DBT85 says is all but maintenance free and is available in 21 colours. Certainly no painting for 15 years+. Three times the cost of timber cladding, but worked better in my build situation than brick/block, which was my only alternative.


----------



## Lazurus (16 Nov 2020)

Hardie board looks the way to go, so would a few courses of brick then a timber frame be the way to go, or would a block inner with insulation and framing then Hardie board cladding be better?


----------



## DBT85 (16 Nov 2020)

Your achitect will tell you whats viable, but I don't think I'd bother with block and then frame the outer. IF you wanted to get really fancy you might brick plinth, frame above with insulation between and then insulated plasterboard the inside which will bridge the cold spots. May be required anyway. No idea for passing building regs. Mine was 29.99m2 so I was allowed to make mine from matchsticks and firelighters!


----------



## Lazurus (16 Nov 2020)

Yes the architect has recommended a few courses of brick, insulated timber frame above this with hardie plank cladding and a pent edpm covered roof with hidden gutters, now awaiting further drawings.


----------



## Blackswanwood (16 Nov 2020)

My ongoing build is being done to the standard required for residential use. It's pretty bog standard brick and block with Kingspan/Celotex cavity board insulation. Due to planning considerations I only had the option using brick for the outer skin but agree the Hardie Board option looks good.

I looked at timber frame construction but the price benefit wasn't there due to the scale. Getting to the standard for residential use was mainly down to the insulation - it didn’t take much.

Your design looks smart with plenty of natural light. Mine needs steelwork to accommodate something similar due to the weight of the roof which your design should avoid also.

Good luck with it.


----------



## Iestynd (17 Nov 2020)

Could you use SIP pannels? Roof and walls, quick to deploy, affordable, extreemly warm and of course can be clad however you see fit. 

Having built a number of extensions within Building regs, i would seriously consider this route in the future. 

Good Luck - I'm very envious.


----------



## Lazurus (17 Nov 2020)

Iestynd said:


> Could you use SIP pannels? Roof and walls, quick to deploy, affordable, extreemly warm and of course can be clad however you see fit.
> 
> Having built a number of extensions within Building regs, i would seriously consider this route in the future.
> 
> Good Luck - I'm very envious.



I hadnt come across these, they look ideal - thank you.


----------



## Shane1978 (29 Nov 2020)

Lazurus said:


> I hadnt come across these, they look ideal - thank you.


Im at a similar (a few months behind) point in my workshop/shed/future-potential-residential-use build. It will be a fair bit smaller than yours (6x4) but I’ve always liked the idea of SIPS. I don’t know many people who have heard of them, and that puts me off (there are so many videos on timber framing, which make me feel more supported information-wise) but if you do consult your architect I’d love to hear what they have to say about SIPS.. do they think it would be easier? What about the cost?


----------



## rs6mra (30 Nov 2020)

Shane1978 said:


> Im at a similar (a few months behind) point in my workshop/shed/future-potential-residential-use build. It will be a fair bit smaller than yours (6x4) but I’ve always liked the idea of SIPS. I don’t know many people who have heard of them, and that puts me off (there are so many videos on timber framing, which make me feel more supported information-wise) but if you do consult your architect I’d love to hear what they have to say about SIPS.. do they think it would be easier? What about the cost?


SIPS have been around for several years and I have yet to come across the downsides to it. I have always always always asked myself the question as to why it isn't that popular. They are easy to erect & have good insulating properties. I wonder what i'm missing......


----------



## Shane1978 (30 Nov 2020)

rs6mra said:


> SIPS have been around for several years and I have yet to come across the downsides to it. I have always always always asked myself the question as to why it isn't that popular. They are easy to erect & have good insulating properties. I wonder what i'm missing......


Do you know anyone with experience building/designing with them in London/South East?


----------



## rs6mra (30 Nov 2020)

Shane1978 said:


> Do you know anyone with experience building/designing with them in London/South East?


Sorry, I can't recommend anyone. My only experience of them is seeing them being put together on several TV programs including Grand Designs and I also looked into it a while back when I spoke to a firm at the Ideal Home exhibition. Some companies that specialise in Garden buildings use them also.


----------



## Keefy. (30 Nov 2020)

There's a company called Future SIPS (in Gloucestershire) that makes garden rooms (could be used for a shed/workshop I reckon).
No affiliation, just investigating what they offer.


----------



## Lazurus (2 Dec 2020)

I contacted supersips with the initial drawing from the architect, in kit form they quoted £14,000 - bare in mind it will still need erecting,cladding, doors windows etc, seems expensive to me over timber frame or even brick and block on 10m x 5m box?


----------



## mindthatwhatouch (2 Dec 2020)

Also look at cedral cladding as an alternative to hardie board. IIRC it’s a bit thicker than the hardie plank.
Thoroughly recommended, I cursed it when installing it as it’s not as easy as timber. But just not having to repaint has already made up for it.

Still find it strange that some authorities accept a timber frame, appropriately clad as non combustible and others don’t. Mine insisted on block!


----------



## mindthatwhatouch (2 Dec 2020)

Lazurus said:


> I contacted supersips with the initial drawing from the architect, in kit form they quoted £14,000 - bare in mind it will still need erecting,cladding, doors windows etc, seems expensive to me over timber frame or even brick and block on 10m x 5m box?


That’s one downside to SIPS, expensive in small quantities.
Also not, adaptable in that the design needs to be pinned down before manufacture, you can’t just ask the builder to shift that window along a bit.

Other than that, as others have said no idea why they are not more popular. Along with metal roof tiles, bitumized boards as sarking/under cladding, or any of the many products/techniques used elsewhere in the world. In my opinion, people just don’t like change, innovation or anything slightly different. We’re still building brick/block cavity wall properties, which other than a bit of insulation, designs haven’t changed in almost a 100 years! 
Other than the fact that the builders now have to wear a high viz, you’d struggle to see the difference between a building site today and one of 50 years ago.

And the look of horror you get from some people if you talk about a timber building, you’d think you’d just farted in their face
I’ve spent a fair amount of time in Norway and Sweden, beautiful, warm, comfortable, adaptable, efficient wooden buildings.


----------



## Lazurus (2 Dec 2020)

mindthatwhatouch said:


> Also look at cedral cladding as an alternative to hardie board. IIRC it’s a bit thicker than the hardie plank.
> Thoroughly recommended, I cursed it when installing it as it’s not as easy as timber. But just not having to repaint has already made up for it.
> 
> Still find it strange that some authorities accept a timber frame, appropriately clad as non combustible and others don’t. Mine insisted on block!




So, with a timber frame, what vapour barrier or simmilar is required between the frame and the cladding


mindthatwhatouch said:


> bitumized boards as sarking/under cladding,


Trying to get my head around the best method from the start.


----------



## gcusick (2 Dec 2020)

Lazurus said:


> So, with a timber frame, what vapour barrier or simmilar is required between the frame and the cladding
> 
> Trying to get my head around the best method from the start.


We did a self-build house about 8 years ago - used a timber-frame package from Potton. The frame arrived as factory-made panels, 140mm studs and OSB panel, with120mm of foam insulation between the studs. The outside was covered with a metallised Tyvek vapour-control membrane. Once the panels were up, a similar membrane was fixed to the inside of the studs, followed by 48mm battens to support internal plasterboard, providing a service cavity. Outside is clad mostly with brick, with a 50mm cavity to the timber frame, or softwood shiplap on 50mm battens.

The house is very well insulated, cosy and toasty!

For a shed, I’d be inclined to fix something like Marley Eternit on 50mm battens fixed to the outside of the timber frame panels, with some cavity ventilation.


----------



## mindthatwhatouch (2 Dec 2020)

Lazurus said:


> So, with a timber frame, what vapour barrier or simmilar is required between the frame and the cladding
> 
> Trying to get my head around the best method from the start.


Don't think there is a best method, depends on the situation, use of building, desired wall thickness, single or double skin, budget, how much insulation you want to put in, and where it is going. etc
If its single skin, I'd go with exterior wood fibre boards, (stops cold bridging better than OSB/PLY) breathable membrane, battens (double battening is a good idea) and cladding. Personally I'd construct so that it could be habitable in the future (or could easily be made habitable)
keep researching, what does the architect advise?


----------



## Keefy. (4 Dec 2020)

Lazurus said:


> I contacted supersips with the initial drawing from the architect, in kit form they quoted £14,000 - bare in mind it will still need erecting,cladding, doors windows etc, seems expensive to me over timber frame or even brick and block on 10m x 5m box?



Future SIPS are a different co, as far as I know.


----------

