Smallholdertoo

Knee pads found - all zip tie tails docked.

I will good idea I have started - it will be done by Friday

Many thanks for your comments - yes it is pressurised and has not dropped since yesterday (no sun either day). Lots of good points to apply

We are due to pour our insulated reinforced raft next Friday. It is all ready except for 1) sealing and tying down a block of XPS attached to the waste pipe to give a void for the shower waste. - Do I need to cover in DPM?, - PU foam around the pipe to seal concrete out - Is tying down the XPS with wire OK. - Should I lift it up from the rebar mesh using concrete "mars bars" to help continuity of concrete and 2) How to protect the pipes under the manifold from over energetic power float operators! Possibly boxing out the area with plywood? Any suggestions on the above or the pour generally would be gratefully received.

Thanks , I will ask the contractor. There will be no contraction joints in the raft- This is a highly insulated house so the UFH will run at a low but stable temperature .Once cured there should be little expansion and contraction

Many thanks that's great to know. Would Mapei's Primer G work?.

@Nickfromwales I would appreciate your thoughts on this matter

We are only looking for up to 600x450 so ok not large format and likely to be 9-10mm thick. I was hoping we won't need a decoupling membrane as low temperature and the tiles being porcelain rather than limestone or travertine!

Thanks we will allow for an inset door mat within the top of the raft by the doors.

Ground works for our new timber frame house starts in a weeks time. The highly insulated 1.5 storey house with a footprint of c.80m2 will be on an insulated reinforced raft, 270mm deep concrete with wet UFH attached to the mesh. The concrete will be power floated to provide a surface for tiling. The water temperature in the UFH should be quite low due to the low heating demand (2kw when outdoor temperature is -9C.) ASHP. I have to order my windows and doors early next week and need spacers under the door threshold to provide for finished floor level. We therefore need to work out an appropriate depth of these spacers to retain a reasonably flat threshold to comply with Part M. We intend using large format porcelain tiles (as yet not chosen) throughout most of the ground floor - except the shower room but am unsure whether I need to allow for decoupling membrane (as recommended by tilers). Taking account of this , how many mm should we allow for the finished floor? The tiler has suggested 17-20mm. Also , how long will it be before I can get it tiled as it is a very thick raft? and should I put the UFH on first. I would appreciate your thoughts as to anything else I should be considering? Many thanks in advance

In a word No! Although it s only a periscope of sorts , it needs to be a1rtight and thermally functional and aesthetically attractive both internally and out. Maybe worth the effort if i needed 5. Thanks for your help.

Contacted Monodraught. They agreed that their Sunpipe is not designed to be airtight, Solatube however do have a passiv house standard version of their product that has 0.5w/m2k u-value and gaskets to ensure that airtightness. So I am probably going down this route.

Many thanks I will contact them on Monday

We are due to start building a highly insulated 1.5 storey detached annexe in July. The downstairs wet room of approx. 4m2 is due to be lit by a small Velux in the roof at the edge of an upstairs. bedroom. I now need to use this area in the bedroom behind a bulkhead for MVHR pipes. My wife wants to have natural light in the wet room so she is suggesting a sun pipe. For me this will only work if it is well insulated otherwise condensation, due to cold bridging, may be a problem. We will have a number of Velux's on the roof so I thought that perhaps a Velux sun tunnel may work. However, these have a basic u-value of 2.9w/m2/k, though they do an insulation kit which drops the u-value to 1.8w/m2/k but only for the 14" version which would be too large for the size of the room. Has anyone used a Velux sun tunnel in a bathroom environment? and if so was there a condensation issue? Or does anyone have any other suggestions?

Thanks for the comments and the support. The SE is yet to confirm the thickness though he has mentioned 250mm in the past. If it does turn out to be 250mm any thoughts how to persuade him to let it be thinner? Its probably worth mentioning that in readiness for the build we have installed 11kw of PVs and 20kw of battery storage on a new shed. This will provide the power to the new house. would this affect your choice of ASHP