pudding

Here's a quick sketch of the detail I'm trying to sort out :-

Hi, Does anybody have any great ideas for a detail on how to finish cedar cladding on a bay window type wall on my new extension, for internal 135 and external 135 degree corners? I'm using some 50x50 Iroko on a couple of simpler 90 degree external corners to match our current house. Ideally we'd also use the same 50x50 ( or close to this) Iroko profile for these 135deg corners, but seems fairly tricky and I've not come across any cladding details for this type of corner before? Any tips?

Hi all, Which of these two, (or any other better details?), would be best for our extension? Are there any problems with either of the 2 details below? The only difference is one has the DPM turned up behind the breather membrane. The thinking behind this is that is protects the bottom of the fibreboard insulation. Any issues? Thanks.

Bit of a thread resurrection! I'm looking at my flat roof buildup. Currently proposed to use the tissue faced PIR. Which VCL did you use and what glue to stick it on? Alternatively, is there any reason or issue against installing the VCL under the OSB? So once the flat roof joists are up, lay the polythene VCL over it and then screw the OSB on through the VCL? Seems like this order would avoid any issues glueing down tissue faced PIR, and the VCL still protects. Ta.

Fall achieved using tapered Kingspan boards. They are paper covered rather than foil so can be adhered to. I haven't yet had a cost from the builders yet but will need to chase them up before they order anything. My initial proposal was for firrings and OSB on the top of standard foil PIR boards, especially as it'll be a green wildflower roof and we'll be walking up there every now and then to trim the plants, so with OSB on top I felt it would be a bit stronger, as I'm not too sure about walking on paper covered PIR boards directly. The builders are keen on tapered boards as everything in the roof structure can be flat and they simply plonk the Kingspan on top. It avoids the need for any extra long fixings for that top layer of OSB, which could need to 220mm+ so would be a lot quicker I guess saving some money there. Thanks for your suggested design. I've sketched it out, so is it something like this, with the supplied rebated timber sat on top:-

This is one idea I have, using a 100x50 Compacfoam block. On the edge of the shuttering for the RC slab pour, a 50x50 batten is attached, creating a 50x50 rebate. The compacfoam can then sit in this rebate, and then in order to attached it to the slab, it is screwed to 15mm ply, which is then bolted to the edge of the slab. Look any good? Lot of faff for not much gain? Not going to work for some reason? Ta.

Morning all, Attached below is the general detail of our foundation/slab/timber frame wall. In this wall we're planning on a 3.6m triple glazed bifold door. Question is how to position the door and reduce thermal bridging. Builders will be pouring a slab next week I think (racing along v quickly, too quickly almost!) so before that really I need to come up with any requirements for the door thresholds. Options in my mind include 1. Simply placing the door on the edge of the concrete slab/inner leaf, with a 190mm cill from the door, spanning over the 100m cavity EPS, but I think this would be the worst thermally, but in the grand scheme of things perhaps not awful? 2. Using some 12/15mm ply to create a box (already doing this for cills/jambs/heads for other windows) that then projects 50mm over the cavity/EPS, and shifting the bifold 50mm out into the cavity/EPS layer 3. Using Compacfoam somehow, perhaps as in the GBS detail, but that then requires those blocks to be ordered and threaded bars, and quite a bit of effort and prep with the pour, so could delay things a bit 4. Using Compacfoam in some other way that doesnt require threaded rods set into the slab? 5 ??? Any bright ideas would be great.

So this is the sketch I've come up with:- Thanks for the replies so far. I'd not really thought about any warranty for the rooflight and would hope a different rebated seat of the same dimensions wouldn't affect the actual rooflight and warranty, but I'm sure they would use it to wriggle out of any claim. I hadnt thought about adhering the roof covering, which at the mo is going to be EPDM to the compacfoam. Anybody any ideas about this and if it could/would work? I'll do some digging for that one. If i go down that route and the epdm wont stick to compacfoam, I could alter the sketch I've done and continue the 20mm PIR up to replace the outer 20mm of the compacfoam and make the rebated section slimmer down to 50mm. Hopefully the VCL blue line I've drawn would satisfy any BCO and is in the right place.

Ah, you've gone for roofmaker, i've got their installation drawing right here! So what insulation is the dark grey, EPS? And why not just one box section, rather than the box and then what looks like a free standing piece of timber next to the plasterboard? How is that piece of timber fixed, what to? It looks like it's the edge of that single piece of timber, then the edge of the insulated box that at supporting the supplied insulated rebate. Is that right?

Hey all, I've ordered a 3g roof light for our 'flat' roof extension, from here - https://www.customrooflights.co.uk/product/flat-rooflight-1000x2000/ Here's the installation section drawing - Our flat roof will also have 150mm PIR on top of the timber joists. I want to try and replace the as drawn 70mm wide timber upstand with something a bit more thermally efficient. I've thought about rather than solid timber, perhaps a 50mm timber frame, infilled with insulation, then another 20mm PIR outside it. Any ideas or tips? Not sure about replacing the supplied rebated timber that the window sits directly onto either. I did consider perhaps as insulated bloc like compacfoam and then cutting it myself to form the rebate, but could be very pricey and not really worth it for the small amount of area? Has anyone tried cutting compacfoam? Seems like from here - https://www.greenbuildingstore.co.uk/product/compacfoam-200/ it'll be £30/m for 75mm blocks, and i'll prob need 7, so a couple hundred quid for the nice thermally broken rebated upstand. Maybe not as pricey as i thought. Cheers.

Thanks for the suggestions. I'll get in touch with another friend who used to work for another local building company and ask about getting a quote from his old co. It's slightly awkward as this builder and quote is from my sis/bro-in-laws old schoolmate, who I've seen quite a few times socially, and he did their extension next door. For that estimators link, which looks good, what docs do they need? Would it just be the 2 docs from the top of this post, the plans and sections from the SE? We don't have any architect drawings, just those.

Thanks for all the replies. Yes, regarding the services I've no idea why they're there. He's been to our house a few times, and knows it doesn't need any new connections of anything. Is this something an estimating firm would just add in a quote as a matter of course? Decorating will most certainly be done by myself, especially considering the current 2 external walls of the house that will become internal don't want decorating, and the large wall in the main extensions room will be pretty much all glazing! Who is the estimating firm do you think? Would the builder get that estimate back and then edit it, as some of the comments relate specifically to my house and things I've mentioned that an estimating firm wouldn't know to add in from the drawings and spec, like lifting the existing patio and relaying afterwards (despite the fact I told the builder I'd do this before they started!) The only way forward seems to be paying for the cost-plus approach and then I'd at least get the see all of his invoices for materials etc before adding his 15% to each one.

Yeah its £2500/sqm ex VAT or £3000/sqm with VAT. Thats the main reason I simply cant go with this fixed quote and would go with a cost-plus deal. I was expecting around £60k ish.

Hello, I've had through a quote from our proposed builder last night for our extension. I'm pretty shocked at the price, and tbh unless we can cut these costs a lot we cant afford it. He said we can either go for fixed price, which I guess would be this quote, or cost plus and I pay as we go with his % added onto everything. The extension is single storey, filling in an area between 2 existing walls of our home. Area is approx 40m2. No plumbing, only electrics are a few sockets/lights, and a feed for an A2A heat pump for heating, although the electrical installation amount looks like just a small provisional amount and isn't a problem and doesn't include the A2A heat pump. There is planned a wildflower green roof on it. The BR plans are below for it. The builders quote is as below:- https://1drv.ms/b/s!AkHh6rqs0aKmn_wZAKkAOrqp1PT3Dw?e=hUO5Kr I don't know if the builder has double counted labour in this quote, as in the preliminaries there is an amount for £18000 + £10800 for labour for the 12 weeks, but then for each item in the rest of the quote there is also a labour charge (adding up to £20469.50, giving total labour of just under £50k?!). Shouldn't it be one or the other or am I misunderstanding this? I've noted a few things that wont be needed, esp in the preliminaries ( the amount of which is the biggest shock!) which can be removed such as all the service connections we don't need or the build warranty i imagine. £18k also seems a lot to me for the ground works and slab, is it? If anyone can see any glaring expensive items it would be appreciated. My current thinking is I'll ask if he can do the prelims/groundwork/structural, on a cost plus basis, and then i'll have to take over due to lack of funds after that.

Thanks for all the replies and comments, I didn't notice them all yesterday. Their should be very little uncertainty and variation with the extension. I've designed it all pretty much apart from the structural elements and there should be no surprises along the way, unless building control come back with a load of issues! I'd already obtained a quote for glazing (bifold/2 full height fixed units/2 top hung windows) which should be the biggest cost item. No plumbing involved, just electrics, which should be minimal. As I've designed and specced so much and will be part time soon, I did want to get involved and do a bit of the work on site and arrange a few subbed items (glazing/matching zinc rainwater goods/a2a heat pump), however the builder replied saying everything needs to go through them with the 'plus', otherwise they couldn't afford their overheads. Which I kind of understand, but it will slightly galling to have to send my glazing quote through them and them add 10% to it when I've done all the leg work and got quotes and visited the company. I've replied to the builder and said to go ahead with a quote using a cost-plus basis. He sent me his terms of business, so i can see their markup etc. It is an extra 15% markup on materials, and an extra 10% on sub-contractors fees, all added prior to VAT. Then these costs will be added to the on site timesheet x labour costs for each bill. Does this sound reasonable?

Yup, that will indeed be the case. I'm lucky enough to earn a good salary and be in the same position as doctors and stuck with PAYE so cant avoid it. Atm, we try and stay below £100k/yr to avoid the marginal rate where you lose your tax free allowance and would have an effective tax rate of 62% above £100k, and one way of doing that was to pay into the pension. A flat 20% relief will now make that a bit pointless and possibly be avoided, and even more of my colleagues will go part time as it's pointless working so hard and long for a little extra money. I'm going part time in a couple of months, and the marginal tax rate did enter my thinking as each years pay rise makes it harder and harder to avoid big tax bills somewhere (other lifestyle reasons were the main factor though, although a drop from 40-20% tax relief will make this issue become more front and center in future, and the end result will be less tax take for HMRC and we simply work less). First world problems tho....

I'm just about to send over drawings to my proposed builder for my extension. He's asked if I'd like a fixed price for the works, or to go with a cost-plus arrangement? Any advice on which could be better and why? I've never heard of cost-plus so some googling is about to happen! Ta.

Mine are up to our garage and it works fine. Think i just put them in each bottom corner of the little trench. It's 10mm SWA i think, and 2xCAT6, about 15m maybe in length.

Thanks for the replies. We'd actually only be heating the dining room (study/bedroom will have carpet so no worries about the floor feeling cold there), which leaves about 28m2 for UFH as an option. I found an even cheaper place here for the kit - https://www.ambient-elec.co.uk/ambient-100w-loose-cable-3653-p.asp which i think makes going for a more complicated heating system of pipes/pumps etc too much, both complicated and costwise. Ed - that was my slight concern that if we run the UFH so we can actually tell its on, then the A2A pump and unit will never run and we'll end up using the more expensive electric UFH to proved the heating. It'll still be useful for cooling though. Does anyone know, do the electric UFH systems just run at full chat until the target temp is reached, no way to modulate? One solution is as you say, is to change flooring type. We were tempted to go with engineered oak as elsewhere in the house, from here - https://www.jfjwoodflooring.co.uk/supreme-engineered-oak-flooring-range-21mm-thick-220mm - I've still got a box of it in the garage which will help keep costs down. My concern with using it is the room will have large bifolds in it, and will be a walkway for kids/dogs and adults from outside to inside, so I worried about wear and tear on it. Maybe an entrance mat/runner and it'll be fine. Certainly the cheaper simpler option and removes the need for the UFH. Hmmm......

Morning, For our new extension which will be approx 40m2, I'm planning on using an air2air heat pump and a couple of wall mounted units to provide the heating/cooling in the 2 rooms (study/bedroom, and a dining room). I've used Jeremy's heat loss spreadsheet which gives a heat loss of 565W for the worst case conditions for just the extensions rooms, so 2 small 2kW units such as these will be ample - https://www.saturnsales.co.uk/Daikin-3MXM52N-Outdoor-Unit-3-Emura-Indoor-Units.html (I plan on feeding the extra 3rd unit into our main house for some cooling) Now, onto the UFH bit. We've got wet UFH in the rest of our house. Unfortunately due to the location of the heat pump and manifolds on the opposite side of the house to the new extension, I don't think getting the wet loops out to the new bit is possible (without major disruption), hence going with the above for heating. However, we're planning on having ceramic tiles in the extension and don't want cold floors, which will be especially noticeable if going from nice warm floors in the main house out to the new extension. Soooooo......my current plan is to put some electric UFH in the extension, solely to take the chill off the floor and just warm it to 15-20degs (whatever feels 'good'). In this case, I think we'd probably need the lowest output UFH you can get. Hopefully this current plan sounds reasonable? Any other suggestions welcome. Floor build up is 150mm compacted hardcore/200mm PIR/150mm reinforced slab/15-20mm tiles. The lowest output UFH ive seen so far is this - https://www.theunderfloorheatingstore.com/electric-underfloor-heating/underfloor-heating-loose-cables/100w-prowarm-loose-cable-kit . If i go for this loose cable rather than mats, I suppose I could space the cable out myself to reduce the overall output, but with the danger of cold spots if the spacing is too great. If anyone has any other recommendations for electric UFH that would be great. Also, do these electric UFH systems modulate their output at all, or is it simply full on until the target thermostat temp is reached and then off?

Hi, thanks for the comments. Yes I was aware it is a hybrid roof. There is no architect involved, I'm coming up with the designs and specs here. As well over 2/3rds of the insulation is above the rafter, as per these links below, then I dont think there will be any issues - http://software.trada.co.uk/techinfo/library/send/3DC53CCF-9477-4190-9287-B4260CDA169D/How to design a flat roof/index.pdf - https://www.partel.ie/news/Flat-roof-construction---an-expert-guide-to-moisture-management/702 I carried a u-value calculation which includes a simple static dew point calc in there and the dew point is not reached until well through the PIR layer so there is no condensation risk to the structural timbers - https://1drv.ms/b/s!AkHh6rqs0aKmnul2ftYxythaIORavQ?e=uZ6cBN

Hi, I've just had the draft building regs drawings from our structural engineers for our extension this week, based on my designs and specs after a few posts on here about it. The plan is to send them off to the LABC for full BR approval. The extension is planned 2 rooms, with flat green roof, timber framed and cedar clad to match our house. Heating is planned to used an air2air heat pump and air con units hung on the walls in the 2 rooms, and also I'm planning on using low power electric UFH with a floor stat only to take the chill off the floor tiles rather than actually heat the whole space. If anyone if feeling particularly bored or has lots of time on their hands, I'd really appreciate any feedback and comments. I've already noticed a few little discrepancies to change but nothing major. Below are links to the 2 docs I've been sent so far. https://1drv.ms/b/s!AkHh6rqs0aKmn4BjENnbHQ-uaVAo0g?e=VpwkbZ https://1drv.ms/b/s!AkHh6rqs0aKmn4BkpFMFIxqIkpMFbQ?e=iHD3oo

So would a unit like this do for my orangery/study extension i'm planning, rather than having trickle vents on the windows?

Whats the source of the heating and the flow temp from that of the water through the UFH circuits?

Here you go - https://www.changeplan.co.uk/u_value_calculator.php