williamlincs

Self build house

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Hello all, 

 

Have been browsing the forum for a few days, time to introduce myself. Im looking to self build a 4 bed single storey house, approx 150 sqm.

I have renovated a couple of properties, and built extensions, but never a full new build. 

What id like to do is to build a house myself, to passivhaus standards. Current thinking is to borrow for several designs in like in terms of layout / elevations, adapt for my site, have a timber frame designed and manage the construction myself. EPS Raft foundation and Ibeam with natural insulation is current thinking, timber clad exterior. I am undecided whether to attempt some level of modularity, I have a big shed i could use to construct sections before moving to site and i like the idea of insulation preinstalled. 

What im struggling with is knowing how to manage the design in terms of orientation / glazing to make it work to passivhaus standards, and i dont know who to use for the design work - im not trying for architectural identity, more performance of the fabric. Any recommendations welcome!

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Hello William and welcome.

 

Whereabouts are you building?

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Or about 500 yds from the sea in 10 years time …. 
 

Welcome ..! 

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Hi, I think sketch-up has a phpp plug-in. If you learn how to use it you can put all your various design options through it.

 

Get passive house plus magazine subscription look for single storey houses for inspiration- you will have a good idea of proportion of window/wall by looking at real life example

 

https://designph.org/

 

Goodluck

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Speak to a passivhaus designer/architect. There are plenty out there.

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Hi William, welcome!

 

To give you a few names, to help with your research, I have an I-Joist frame from Touchwood Homes.

 

I hope Touchwood are still running, but I notice their website is down. They do have a FB Page, although that's not seen any recent activity. Touchwood specialise in PassivHaus timber structures.

 

I've noticed one of the brothers, Reuben, has started up a new venture. Mango Projects. They look to be advising on PH builds as well as designing and installing MVHR systems and other services. Reuben appears to have Dr. Rod Williams, of Williams Energy Design, working with him at Mango Projects. Rod is, amongst other things, a 1st class PHPP designer and would be able to help and advise the most appropriate layout of your site, as well as getting into the detail design to deliver the best possible performance, for a budget. Rod did my PHPP design.

https://mango-projects.co.uk/2020/05/28/who-are-mango-projects-ltd/

 

Touchwood's timber frames were/are designed and engineered by Cullen Timber Design. They'll design any type of timber structure you want, but, with Touchwood, they have developed a very simple, high performing build process, and are very used to designing out cold bridging etc. for PassivHaus builds. 

 

http://www.cullentimberdesign.com/

 

With Touchwood Homes erecting the Cullen Timber Design frame, and filled with blown cellulose fibre insulation, they guaranteed better that 0.2 ACH air tightness, and often achieved better than 0.1 ACH, as they did with mine. And all without an air-tight membrane, just foil backed plaster board, on to the I-Joists and externally sheathed in T&G Egger DHF sheathing board (with a few construction tricks to ensure air tightness). The DHF board is the air tight layer as well as the racking strength, so no need to OSB internally, unless you want a service void.

 

I used Advanced Foundation Technology (AFT) for my EPS insulated raft. AFT have done a number of rafts to suit Touchwood's I-Joist structure, and have a very simple solution for eliminating any cold bridging. As well as engineering the foundation, Olof at AFT will also come to your site and help you install it, incl. UFH, if you supply a couple of labourers

 

https://www.advancedfoundationtechnologylimited.co.uk/

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Welcome welcome.

 

I love the sound of your project in a smashing part of Britain. 

 

If you can spare the effort,  get a copy of PHPP. It is a tremendous learning tool if nothing else. 

 

I would employ a proper passivhaus designer who takes overheating seriously and builds in proper measures to counter this passively. 

 

If i had the choice again I would build like that, timber + cellulose, ace. Blown in insulation on site wins for me. No waste, No settling in transit. You could get some joiners and build panels in your shed no problem. 

 

A couple of single story houses that caught my eye browsing the web.  

 

Cousins River in the US.

https://www.gologic.us/1700-model designed by https://opalarch.us/portfolio-item/cousins-river-residence

 

Old Holloway.

https://passivehouseplus.ie/magazine/new-build/deep-green-passive-house-defies-all-weather

https://oldholloway.wordpress.com/

 

 

 

Your chosen build method sounds like a couple of projects from Mike Whitfield and Dempsey Decourcy. 

 

Ty Pren

https://passivehouseplus.ie/magazine/new-build/the-west-midlands-eco-house-with-no-energy-bills

 

Good luck!

 

 

 

 

 

 

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Thank you all so much for the warm welcome!

 

@PeterW  Floods of 1952 came dangerously close to where my site is. Its a real worry for everyone in Tourism/Agriculture here. So much land, particularly south of Skegness relies on the internal drainage boards to mechanically pump water out to sea.

 

@Donegalsd Thank you for that tip

 

@IanR Wow, this is a great list, many thanks. What was the build up of your roof construction? Same as walls? By racking you mean bracing between the verticals?Does the DHF then preclude the need for an additional permeable membrane? battened and then counterbattened and your cladding on top? No tape sounds excellent. I had been looking at Hempcrete, simply because Warmcel seems to be 3rd party installation. I suppose doing it as a similar way as you have done would make off site not feasible.

 

@Iceverge Old Holloway is exactly what i had in mind! Thank you!!!!

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2 minutes ago, williamlincs said:

 

@IanR Wow, this is a great list, many thanks. What was the build up of your roof construction? Same as walls? By racking you mean bracing between the verticals?Does the DHF then preclude the need for an additional permeable membrane? battened and then counterbattened and your cladding on top? No tape sounds excellent. I had been looking at Hempcrete, simply because Warmcel seems to be 3rd party installation. I suppose doing it as a similar way as you have done would make off site not feasible.


Roof is same build up as walls. I just have 350mm I-Joists in the Roof, where as 300mm in the walls. This is where PHPP comes in to it's own, and shows you where to spend your money. Single storey Buidings, with their proportionately larger roof area, benefit from more insulation on the roof, and PHPP gives you the sweet spot.

 

Yes, racking is to stop lozenging of the structure. Most timber frames would have an OSB layer for this, but the DHF allows you to avoid it.

 

You do need a breather membrane on the DHF to protect the structure. I have standing seam on the roof, so it's battened 50x50 for ventilation and then 18mm OSB deck, another breather membrane and standing seam on top. For the walls I have a mixture of horizontal and vertical timber cladding, so either just battened, or battened and counter battened.

 

The foil back plaster board takes care of the vapour barrier, so no separate membrane needed. The build-up can easily shift a bit of moisture so you don't need to be too anal over penetrations in the PB for switches and plugs etc. - electrics can run in the insulation, it just plumbing you'd need to run a service void for.

 

I'm not familiar with hemcrete, I'd assume it has a good decrement delay ie. +12hrs, but you should check. Blown cellulose really does, so makes the build up perform better keeping a more stable internal temperature. If you've not got a masonry skin, it's really important to have an insulation with a long decrement delay. 

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19 hours ago, IanR said:

With Touchwood Homes erecting the Cullen Timber Design frame, and filled with blown cellulose fibre insulation, they guaranteed better that 0.2 ACH air tightness, and often achieved better than 0.1 ACH, as they did with mine. And all without an air-tight membrane, just foil backed plaster board, on to the I-Joists and externally sheathed in T&G Egger DHF sheathing board (with a few construction tricks to ensure air tightness). The DHF board is the air tight layer as well as the racking strength, so no need to OSB internally, unless you want a service void.

 

Very interesting. How did they blow in the cellulose? Did it require holes to be cut in the plasterboard? I assume services were threaded through the i joists? Do you have any pictures with the wall "open" . 

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I'll have a look for pictures.

 

Cellulose was blown in through 100mm holes in the PB, which is a down-side as they all need to be but back in. Yep, wiring through the webs of the I-Joists and down the lengths of then. Very easy for penetrating the outside (airtight) sheathing and gasketting all the holes to seal..

 

Edited to add:

 

Here's the only image I have of cabling into the insulated area...not much good.

 

image.thumb.png.bb88973317bc52503e692de5a4f5ebcf.png

 

But some more general ones of the frame

 

112.thumb.JPG.58766602db96773aa1f8cce60f78db5b.JPG

 

111.thumb.JPG.03df5c1f422495e59a6902cb84cbc599.JPG

 

113.thumb.JPG.ce2e466f787e758723b7d53507357ea3.JPG

Edited by IanR
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Tops. That jobsite is immaculate. 

 

The system reminds me of methods used in the States. Did you run any pipes in the walls? 

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No pipes run in the insulation. I couldn't avoid a service void in one room ceiling and external wall to get some pipes to some taps.

I've got wall hung WC frames on a couple of external walls, but just put them in a false wall.

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@IanRThats a big house! Were all the i-joists pre-cut or are they delivered in standard lengths and cut to size on site? What is the purpose of the beams located outside the upper face of the trusses running perpendicular?

 

Would you mind giving an indication of cost p/m2 of the Warmcel for your build?

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1 hour ago, williamlincs said:

@IanRThats a big house! Were all the i-joists pre-cut or are they delivered in standard lengths and cut to size on site? What is the purpose of the beams located outside the upper face of the trusses running perpendicular?

 

Would you mind giving an indication of cost p/m2 of the Warmcel for your build?

 

It's a converted Cow-shed. 465m² foot-print. All habitable space on the ground floor, due to planning, but a 6.5m ridge, so +200m² of height restricted "storage" on the 1st floor.

 

Cullen Timber Design can send a full cutting list to JJ I-Joists, and send a set of Assembly drawing for you to put together. But Touchwood did a half-and-half. Difficult cuts to measure cut by JJ I-Joists, and then several loads of 13m joists that they cut on site.

 

116.thumb.JPG.d7889a78d9c57b33796282d1b5daaf8e.JPG

 

Sole and Eaves plates were all pre-cut and had a 3mm deep slot cut for every upright beam position into. Once Touchwood got the sole-plates laid out and fixed, all the uprights just got placed in with barely any measuring. Accuracy was first class. Window openings were within a couple of mm.

 

114.thumb.JPG.14f1c40579159d3abe245bb5350a18d6.JPG

 

My Warcell areas were 196.6m² of 300mm thick & 416.4m² of 350mm thick. 26 bales in total, installed by Payne Insulation (Norfolk) for just under £15K.

 

They were grumbling at Warmcell's pricing going up and up back in 2017, and were talking about a cheaper alternative from the Czech Republic, that was pretty much the same product.

 

Not sure which beam you are referring to. On which Picture?

 

115.thumb.JPG.6b0bc33e8dd14dc4791cf99b85230ab0.JPG

Edited by IanR

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26 minutes ago, IanR said:

 

 

115.thumb.JPG.6b0bc33e8dd14dc4791cf99b85230ab0.JPG

Jesus that's impressive. Very very cool and mahassive!  Very tidy also.

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@IanR I see now, the beams i was looking at were the z sections in between the steel portals! One thing that keeps cropping up with my design being single storey is the form factor issue, and Passivhaus standards being easier to meet with 2 storeys. How did you you mitigate this with an expansive ground floor plan? 

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10 minutes ago, williamlincs said:

@IanR I see now, the beams i was looking at were the z sections in between the steel portals! One thing that keeps cropping up with my design being single storey is the form factor issue, and Passivhaus standards being easier to meet with 2 storeys. How did you you mitigate this with an expansive ground floor plan? 

 

Ah, yes, the original Z purlins. While most were replaced, I had to keep the Z purlins to keep the original structure standing.

 

Going through the PHPP process, It didn't feel like the single story was a negative (but I agree it is), you just keep tweaking different aspects until you get all the requirements in the box. I've not had to go for an excessively thick insulation to achieve the targets. The hardest "negative" to mitigate was the amount of glass I went with, and no opportunity (due to planning) to build in fixed shading. This was an over-heating issue, resolved with external blinds and tinting on the roof lights.

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56 minutes ago, williamlincs said:

@IanROne thing that keeps cropping up with my design being single storey is the form factor issue, and Passivhaus standards being easier to meet with 2 storeys.

 

Just add more insulation. PHPP makes it easy to see what the best trade off is. 

 

Passivhaus is definitely easier to satisfy with a larger squarer building but you can get passivhaus performance in a compact cottage without reaching the passivhaus levels. 

 

https://passivehouseplus.ie/magazine/insight/the-small-passive-house-problem-a-solution

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We've hit passive requirements with our there story, L shaped house with lots of glazing. Just stick in loads of insulation.

 

 

 

Edited by Conor

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