Rishard

What uvalue dis you achieve with this insulation set up? Did you stick with the 150mm pir + the mineral wool between? I like the concept as it’s a pain fitting pir in between. Mineral wool is much more forgiving but doesn’t pack the same punch and requires greater thickness. Full sheets of Pir externally over the top sounds dreamy, minimal cuts and good performance. I’ve looked at this type of warm roof with wood fibre as the external insulator but the price per m2 is twice as much as Pir and half as effective (in a warm roof) it’s hard to justify. Any other iterations of warm roofs which don’t require 300+mm rafters?

I guess the further down the fixings the more stability? Once the noggins are all in between the rafters and the blockwork the strap just locks it in place. If the fixings were only in the top block then it had a higher chance of that block becoming lose? If the fixings ran further down the wall into bonded blockwork I guess this would help a bit?

In hindsight maybe a warm roof would have been best in this situation. I’m a bit limited with head height on some areas of this build as 2 rooms have low eaves (1.8m) if I was to move over to a warm pitched roof I’d have to lose the height internally. Not entirely out of the question. I may look into my options regarding this. Thinking off the top of my head, I have 200mm rafters which i planed to fill with insulation. If I introduced a purlin mid span I could reduce my rafters down to claw back potentially 75mm from the rafter thickness. i wonder if I could use a really long straight restraint strap (2m) and bend it down 800m into the cavity for more fixing points and have 1200mm across the underside of my rafters.

That all sounds pretty sensible and practical. A much easier approach then trying to get the plaster in to skim a meter strip around the whole joist band area. Will look into airtightness paints next. My eco joist supplier is able to provide my joists with an amount of ‘trimmable’ ends in order to get the best fit. In reality it is much more difficult building up all the masonry 2 storeys without the first floor to work off. We’re about done now so looking forward to putting a roof on and installing a floor.

The inner skin of blockwork is often cut to just below the rafter top. Is there any reason it couldn’t be left a little short and cut to the underside of the rafter? In this situation it would allow my cavity insulation to connect to my roof insulation (insulation between rafters) I could still mount restraint straps to the underside of the rafters however the straps wouldn’t be ‘built in’ and they would need a masonry fixing to the blockwork. Most of my ceilings are vaulted / cathedral ceilings.

I hear what you mean regarding the cantilever. I will have a word with the sparky and see if a pre planned conduit run or chase could work behind the ledger. In regards to airtight paint. Do you mean seal the top and bottom edge of the ledger to the blockwork? Would an airtight silicone type mastic be good for this if the timber shrinks? Never used airtight paint direct to blockwork/timber. Am I right in thinking you’re talking about applying it at this junction, prior to plastering?

In relation to this topic. I’ve installed ledger boards in the past with resin bolts and had good success. I haven’t ever wet plastered behind the ledger boards. Would you just wet plastered the area behind the board before installing it or the whole room? Obviously difficult if there is no floor in yet. I plan on using ledgers with my design and eco joists on 400mm centres. I remember once spacing the ledger off by 25mm behind the each resin bolts and had so the electrician had an easy route down for his cables. Do we think this is advisable or should be avoided? I have a concrete ground floor so imagine most of the socket ring main and lighting coming down from the first floor void.

We often over size the ‘height’ which allows for some adjustment up the roof to work with your roof tiling/flashing kit. Once the window is fitted the opening should have a plumb piece of plasterboard running into the low side of the velux and a horizontal plasterboard to the head. This allows air to flow in and then out of the velux reveal. All standard practice and outlined in the fitting instructions. The rough framing is always better left taller on height to allow for this. Hope this helps. Width is usually 40mm oversized for perimeter insulation depending on supplier.

@saveasteading love the look of this roof. Who did you use for supply of the panels? Also, what make up did you use below it? Cheers

+1 to external glazing. I’ve built several oak frames this way. It’s a bit of a hybrid as the cover boards which sandwich the glass to the oak frame are separate pieces of oak which on a traditional ‘oak frame’ is a bit false but I’ve not seen a better system out there. If the cover boards are rough sawn then it looks best. We use expanding foam tapes to seal the frame to the glass and glass to the cover boards. These are weatherproof and adjust with the shrinkage of the oak. Oak frames are harder to airtightness seal and have some fairly substantial thermal bridges but it can be done. Oakwrights system is good.

Resurrecting this thread. I’ve had a price from vartryengineering. It was quoted a while ago but came in at €1.33 each. Did anyone find a cost effective alternative at all?

Where did you decide to tie your UFH pipes in the end?

That’s helpful information. Ideally the guest shower room would have wet room plumbing for the shower. I still need to look in to how to achieve this. Is it just w/c’s that want a direct route to IC? Are basin wastes ok going into a Y in a pipe run? Same with kitchen sink, can that be in the run that connects to the stack which runs upstairs? Swept bend at base of the stack joining a Y coming from kitchen sink to IC?

I forgot to mention, I’m using pozi joists for this build. Which have a 200mm clear space between the cords which I can as planing on using to service the master en-suite. The w/c would have a basin, just not on the plan. Could the guest shower room not link to the drain run coming from the w/c? I have plenty of fall to the main drain so can set my bends very low below the slab if it helps. I don’t like the idea of drilling holes through the wall to connect up externally. Ideally most should come up through the slab.

I’m just about to set out some of my 110mm soil pipes. On the architects plans we have picked the shortest route to the outside of the building which seems sensible. I have a kitchen waste at the rear of the build which on plan is going around the outside of the house to join the other soil pipes. My first question is, Would it make sense to try come through the building to join the other soil pipes as a more direct route? Or is this a plumbing no no for some reason? My second question is, The 2 soil pipes which are in the utility and wc/shower room. I’m imagining a swept bend coming up to a vertical pipe through the slab. Is this the point where all the shower room and w/c connections are made or should I have 1 for the w/c and 1 for the shower room as they are separate rooms? Which of these pipes needs a rodding eye if any? I gather the stack which runs up the utility to upstairs will be ok to have an AAV in an accessible place, is this correct? Thanks in advance I have attached floor plans and foundation plans.

Great, so it is 100w used per hour to achieve the desired temperature. It’s good to clarify. When you put it together as 2.4kWh over a 24 hour period it becomes more of a worth while saving. Apologies for my basic understanding, I’m getting there. Believe it or not I have had phpp done for my house. 1. He did explain a good amount with me but I wouldn’t know how to work out how many cold days a year from it…. 2. current electricity 0.30 kWh 3. 20 years + 4. Not till it’s built but probably not much longer. I do care about its performance over its lifespan. This will be my family home so will have to live with the decisions…

Is this a 100w difference in heating per hour? I’m costing out insulation to fill the cavity, it’s a similar cost to concrete by volume. Obviously I don’t want to fill with concrete but I’m trying to grasp where the cost savings sit. Say I add 50mm pir to the inner face, that’s £400. Again, not going to break the bank but the question is, will it save me money in the long term?

Returning to this one, am I right in thinking xps insulation for the cavity is better than eps? The green building store said the xps held its insulating properties when in wetter environments. I’m hoping mine won’t be getting wet but it’s worth hearing other opinions.

Joes detail which is taken from the golcar house has a dpm wrapped around the top block to try avoid it being ‘wet’ as you describe.

My perimeter is 50m so assume it’s closer to what iceverge suggested. Although I’m not the best at working these things out…. Yet

It’s very helpful to see the small increments in improvement and its relative impact on the watts. If I use 60m of insulating blocks for 2 courses it still comes in at under half the cost of the marmox blocks. Would the £600 difference pay itself off in energy saved? If not then I may be happy with using detail 4 and move on to other decisions.

So if this detail fails SAP then it only leaves marmox blocks right? Does this mean everyone is going to be doing this detail?

I know Marmox blocks are great for this kind of issue. In your drawing are they laid on the inner skin? They’re pretty dear, I know that much.

So I’m using 200mm pir insulation and have a suspended slab which loads onto the internal skin. It’s great to see some of your calculations, I wish it was something I was capable of or had access too. So from what you have said, there is little benefit in laying aerated blocks anything more than say 1 or 2 courses below my slab? Would you say to cavity fill with insulation down the whole 900mm to foundation top or would laying it down to say 600mm be adequate. My floor build up is, top down, 150mm slab, 200mm pir, 160mm void formers in some areas( ‘ground heave’) 150mm hardcore.

Morning, you’re right regarding pressure on the cavity. I have my SE looking at this today to see if the insulation in the cavity is up to it or if we maybe need to use a block on its back to help be or partially fill the cavity up to a point. Regarding the 50mm pir down to foundation, if the slab is suspended, like on the drawing, does the cavity insulation below dpc do a similar thing or is the 50mm pir reducing the heat loss up the insulating block to underside of slab? Mine will be a heated slab.