Newbie Here From Leicestershire. Question: SIP, Timber Frame Or A Hybrid For A New Build Dormer-Bungalow?
Posted 23 November 2015 - 10:30 PM
My names Harvey and I am new to this forum. I have read several threads but don't think I have found one that completely helped me with my questions, hence why I'm on here now.
I have planning permission for a dormer bungalow, I would like to be involved as much as possible with this build, but I also know my limitations too. I would like to have the 'shell' built/erected to water and wind tight, I believe this is beyond my capabilities so would prefer this be done by professionals. I initially thought 'Brick and block' would be the way forward. After making a few enquiries I soon realised that there was too many variables and I was reliant on different trades to work in sync.
I have now realised that either TF or SIP's is the way forward. I have made several enquiries and and still waiting on a couple of quotes to come back. The dormer bungalow comes to approximately 330 SqM.
I have had the following quotes, I will keep the companies anonymous:
I have had a local reputable firm quote me £46,000 delivered and erected. This includes:
- 140mm deep studs with factory install 120 PIR insulation to external walls sheathed with 9mm OSB
- Reflective external membrane
- Trussed roof and dormers (no insulation)
- Cavity battens with TCB cavity barriers on external face to suit 50mm clear cavity
- I beams (Centres not specified) 22mm chipwood decking
- All Steels
I will obviously need to insulate the dormers and the roof, this will require some man hours and a lot of attention to detail to make to get the air tightness etc. No U-values have been quoted.
I've had a national reputable firm quote me £60,500 for 142mm(0.18 U-Value) and £65,000 for 172mm (0.15 U-Value), both using Kingspan Tek panels.
- Kingspan Tek system with the sip spline (I understand this is better for thermal bridging?)
- Factory fitted vapour control layer
- Service battens to external walls
- Glidevale TF200 'Thermo' breather membrane (Not sure if this is a decent quality)
- Vaulted ceilings (I like the idea of this as I plan to have full height ceilings in the main bedrooms and storage etc above the 2 smaller bedrooms)
- Metal web joists @ 600 centres (I prefer these for ease of first fix etc)
- All Steels
I can alternative have the following combinations from the same national company and the prices are not significantly different.
Timber Frame 0.18 U-Value + 142mm Kingspan Tek 0.18 U-Value Roof for £57,500
Timber Frame 0.18 U-Value + 172mm Kingspan Tek 0.15 U-Value roof for £62,000
The timber frame supplied by the national company is closed panel and also has service batons to the internal face.
Sorry for the long winded question, I thought I would give as much detail as possible. My questions is which system is best suited for me considering I'm only interested in doing the internal works myself. The first timber frame system require me to hire in a 3rd person to insulate the roof and felting it. If i have problems with this trade, the whole house could potential be at risk in adverse weather. This maybe £10k cheaper but i need to insulate and get air tight etc. Is there any feature or something obvious that I am missing?
If I go with the national company, which setup would you recommend and why?
here are there 4 systems to summarise
£57,500 Timber Frame 0.18 U-Value + 142mm Kingspan Tek 0.18 U-Value Roof for
£60,500 Kingspan Tek 142mm 0.18 U-Value
£62,000 Timber Frame 0.18 U-Value + 172mm Kingspan Tek 0.15 U-Value roof for
£65,000 Kingspan Tek 172mm 0.15 U-Value
The price increases are not huge in comparison to the overall spend on the house. Would I notice a difference between U-values of 0.18 & 0.15?
I am a newbie here and so apologise if I have misunderstood the code of practice for this site. Please also forgive me if I have used the incorrect terminology as I'm not a builder by trade, I just love giving this a go.
Any advice would be greatly welcomed. Thank you all in advance.
Posted 23 November 2015 - 10:39 PM
What sort of external wall finish are you looking for? I'll bet the standard timber frame quote is expecting you to build a brick or block outer skin (they mention a cavity)
Posi joists are good, as is a vaulted ceiling supported on a ridge beam. Neither are specific to one build method and you can use them with a timber frame, sips or even brick and block. A vaulted warm roof is probably easier to detail the air tightness.
It is a minefield trying to build a good quality house. There are a handful of companies that specialise in this like MBC, Touchwood, Beatie Passive etc, all worth a try. Or you can do as I did and seek out a local builder that actually understands low energy houses, insulation and air tightness.
Edited by ProDave, 23 November 2015 - 10:43 PM.
Posted 23 November 2015 - 11:05 PM
Thank you for the quick response. Sorry for not including all the details you speak about. I felt my initial post was getting long and didn't want it to drag.
As mentioned by a regular blogger to this site, there are very few companies that will do the foundations too. He did mention a particular company from Ireland and I am still waiting for a quote off them for the Frame & foundation. If I find this is out of my budget, I will use a local grounds person to strip pour the foundations and I a brick layer to lay the trench blocks. I have had quotes for the dig and pour of the foundations and the bricklayer is willing to wok on a day rate. I will then 'attempt' the drainage myself.
I would like to go for grey Marley Edgemere roof slates, both the companies are aware of this and I assume (naively more than likely) that they have allowed for the weight of this.
The house will have approx 180 SqM brick clad and approx 110Sqm or render. I was thinking of applying cement boards after leaving a 50mm void to the shell and then have an elastomeric render applied to it.
I have also looked into the doors and windows, but not as thoroughly as I would like to yet. I am leaning towards Aluminium and I have Bi-folds in the plans and I understand Aluminium is best for these? I was thinking of a dark grey finish and I hope i'm right in thinking they don't fade their colour as some of these UPVC windows do?
I could be inclined to swap the render for some sort of timber clad, I would feel confident in attempting this myself too. I'm not familiar with vlock, could you please perhaps elaborate?
I do like the vaulted ceilings but the span is just over 6m, I understand i will therefore possibly need a purlin (not so keen on that). The company said they usually achieve a good level of airtightness (I think i heard a value of 2 units being mentioned).
I am in fact in the process of getting a revised quote from MBC, their initial passive house quote has very impressive U-values and a great understanding of the process. It was unfortunately significantly higher in price and there fore out of my budget. They looking to see what they can offer with a slightly different specification.
I could pay the extra money for a builder who understands these matter much better than I do, but then I suppose I would have to compromise on something to offset the cost of said builder. I was hoping for all your expert advice on this forum and help me better understand how to build to a high standard.
Thank you for your time so far ProDave. I welcome any other comments and questions.
Edited by harvey, 24 November 2015 - 12:15 AM.
Posted 24 November 2015 - 09:42 AM
330m² is a big bungalow.
Whereabouts in Leicestershire btw? Nice to have someone local, everyone else seems to be building somewhere more interesting (but I like it here, Vale of Belvoir/Melton).
Posted 24 November 2015 - 09:59 AM
Don't get too hung up on a real brick skin. It adds almost nothing to the insulation of the building as the cavity has to be left very well ventilated. Ours is being clad in 100mm Pavatex wood fibre board onto which a lime based render is applied.
Very few bricklayers have the accuracy for a timber framed building. We were careful that we appointed one company to build the foundations and build and erect the timber frame, so any discrepancy in size between the foundations and timber frame was their problem. As it happens their bricklayer was extremely particular and accurate and everything fitted perfectly.
Our house is 7 metres front to back and there is no trouble spanning that with a vaulted ceiling supported just on one big ridge beam. Things like that will need input from a structural engineer to size the beams.
We are having Rationel aluminium clad doors and windows. Of all the companies I approached they were the cheapest, and the second best in terms of Uw value. (only Internorm offered a better Uw but at twice the price)
If you are going to be doing a lot of work yourself, including the drainage, consider as I did and buy yourself a mini digger. That's been my best buy for the job yet and will be sold once it's all finished. (second best buy was my scaffolding)
Posted 24 November 2015 - 10:03 AM
Posted 24 November 2015 - 10:05 AM
Thank you for the heads up on the bi-folds, I've had a few quotes come back and the costs vary considerably. I visited the NEC earlier this year and met a few companies who supply doors and windows, it's very hectic at these shows so I will do some reading up and look for threads on here for recommendations.
Yes 330m2 is a fairly large bungalow with a190m2 on the ground floor. I need the whole of the ground floor wheel chair friendly and this design has let me do that.
It's great to see others who are local too, I'm in Field head which is on the outskirts of Markfield. I've unfortunately never visited Vale of Belvoir but hear its beautiful, We're up the road from Bradgate Park so enjoy the views here!
Thanks again and we will chat again hopefully.
Posted 24 November 2015 - 10:09 AM
Posted 24 November 2015 - 10:43 AM
I am hoping to get the house up ready to be tiled by end of Feb/March. I would love to learn to tile the roof but I think this is too big for me to take on and it would be money well invested getting this fitted by a professional.
I do quiet like the rendered finish but I feel the design my architect has put together needs bricks as he's shown on the plans. I did have a discussion with the architect but it made sense in what he said. Maybe I need a second opinion on the finish from someone independent and done more work with these modern renders.
ProDave, you said you're cladding with 100mm Pavatex wood fibre board and applying a lime based render. I assume you've got a SIPs or TF? Do you have an OSB exterior on your build and if so, can you fix external insulation to it and render without a cavity?
Ideally if MBC come within budget I will have the do my foundations, failing that I plan to get the foundations drawings from which ever company I use and then have these build by local firm. Once ready I wanted the company to come out and check the dimensions, levels etc and then they manufacture the kit. This will hopefully leave less room for disagreements as to who's fault it is.
I was wondering what accuracy do bricklayers lack with TF buildings? I (and perhaps naively) thought they need to be able to lay bricks in nice clean lines and get the window and door reveals right. I'm not entirely sure how or what is used to span the gap between the TF and brick clad cavity space (I'd like to fit the windows flush to the outside of the TF building). How does the brick layer openings to the correct size without over shooting or finishing too soon at the window opening?
With the point I made about not wanting a purlin, I don't think i was clear with my dimensions. The room spans 9m and the length of the truss from eave to ridge is about 6.4m. Can this be spanned with SIPs without a purlin?
Thank you for the recommendation on the windows, I will ask them for a quote, may I ask what U-values they quoted for doors and windows?
I do like the idea of buying a mini Digger and selling once I've finished the job. I can learn how to use it as I go along, I am a little concerned that if it needed repairs then I'd being good money for an engineer to come out. I have decent car mechanical knowledge but I guess a digger will be very difficult. How reliable are these things? And i guess the newer the digger the less likely it'll go wrong?
Temp, thanks for your comments, what are the issues with insulating yourself? Would poor fit and handling be part of it too?
I look forward to your replies, thank you again for reading and for all your time.
Posted 24 November 2015 - 01:10 PM
For windows doors etc you set it out correct at the bottom. Use a tape and work out where all the openings are and set your bond to suit. Might need to tight perps or even slightly open them up to suit. Same again if you cant do this then stick to pig houses.
I tiled my own roof and its not as hard as you think. It's more time heavy than being hard with the actual tiling the easy bit. It's all in the spacing out of the battens and setting out your straight lines. Have a good few tips if you need come that time.
Bi folds aren't all they are cracked up to be. Apart from being so expensive the seals will go in them after no time at all esp if you are going for a black finish.
The problem with room in the roof type houses is that unless you are on the ball with details it can be a mess. If you are doing it yourself you will spend more time and do it right. Don't cut pir boards up. Use higher density rafter roll or similar or get it blown in.
Posted 24 November 2015 - 01:21 PM
It's detailed here. http://www.ecomercha...ime-render.html
Click on "technical information" and download the PDF brochure.
Page 6 of the brochure shows the wall make up with the OSB as the inner skin and the wood fibre on the outside.
There's no cavity and it means a 300mm thick wall is 300mm of insulation. Compare that tot he average timber frame house where you are lucky to get 200mm of insulation.
Posted 24 November 2015 - 05:56 PM
I'm fairly confident I can get the foundations to within the +/- 5mm tolerance both the companies have stated. I think the windows and doors will require a lot thinking. Am i right in assuming that windows and door openings in Brick and block builds are usually determined by where full or half bricks finish on the external skin?
I might take you up on your kind offer of some handy tips. Although I'm in no real rush to complete the project, I am aware it's not ideal to leave the roof with just the breather membrane/felt alone. So I'll have to do some calculations on how long it may take me to install them, I certainly would like to learn how to tile but need to weigh up if it makes more sense to get someone in to do it quicker and invest my time elsewhere and where my feet are on a flat surface preferably.
What, if any is the best solution to Bi-folds?
I'm more inclined to go with the SIP's panel roof to overcome the issues you mention about cutting pir board etc. The kingspan tek panels are a continuos insulation with no timber trusses and have sips splines where the joins are.
So I'm still no closer on a decision of a SIP's wall or Timber frame walls with the previous mentioned U-Values. Any advise/suggestions would be welcome.
Edited by harvey, 24 November 2015 - 05:57 PM.
Posted 24 November 2015 - 06:07 PM
I've had a look at the system and it seems rather interesting. Very different to anything I looked at to date, do the same company or someone else supply the reverse wall construction timber frame? Am i right in understanding that with 200mm stud and 100mm you will achieve a U-Value of 0.15?
I do like the finished lime render, if you don't mind me asking, do you have an approximate square meter price of insulation and render installed?
Posted 24 November 2015 - 07:01 PM
Instead of bi folds we went with French doors with two side lights.
If your no good with heights then a roof is not the place for you.
Posted 24 November 2015 - 07:08 PM
I haven't costed the finished wall per square metre yet. In particular I haven't yet costed the blown in insulation as that's not on the "critical" list it's on the "when we can afford it" list. Our priority being to get the building externally finished so it's safe from the weather. Likewise I am still waiting for a price for the rendering. the guy has failed to turn up on two appointments so far which does not bode well. I have seen his work however and I liked the slightly off white slightly roughcast finish.
Posted 24 November 2015 - 07:21 PM
I have a 4.8m opening from the kitchen that is facing East, I really like the idea of the large opening but don't like the sound of these seas going within a year or so. The opening is too wide for French doors.
Not too far to fall off a bungalow roof though i suppose
Posted 24 November 2015 - 07:29 PM
Lime render does have that roughcast finish as supposed to some of the new renders which can look very clinical.
Posted 24 November 2015 - 07:53 PM
ICF is a reasonable choice if you want solid masonry, as that gives you freedom from cold bridging, inherently good airtightness and a reaonably high decrement delay factor.
At the other end of the scale you have slim (150mm or so) timber frame and SIPs, where cold bridging can be a problem, decrement delay factor will be short and insulation barely above building regs.
You can build very well insulated timber frame houses, but there are plenty of gotcha's. It is ABSOLUTELY essential that the insulated foundation design is a PERFECT match to the walls, to avoid the critical wall/floor cold bridge and associated interstitial condensation risk (a big developer is currently dealing with internal rot in houses built in 2007 because of failing to do this).
Some companies offer a foundation, build and insulation package, some wit guaranteed airtightness. Well worth the extra cost in my view, as it gets rid of a massive amount of risk.
Questions to ask of any builder:
Do they offer an integrated cold-bridge free insulated foundation system?
Do they guarantee the insulation and airtightness to reasonable levels (walls around 0.12 to 0.14, floor and roof around 0.1, airtightness better than around 1 ACH)?
Posted 24 November 2015 - 08:36 PM
After looking around, I think my budget will stretch to a 172mm Kingspan Tek SIPs house offering a U-Value of 0.15. The thermal bridging from panel to panel is good too as they use a SIP's spline to connect the panels. I still need to check the detailing at the wall/roof joint asI assume this is an area for potential problems.
I will put these questions to them and see what they come back with, I suspect they're only interested in supply and erecting their panels but we shall see.
Thank you for looking over this for Mr Harris.