WWilts

Minded to follow this general approach, using timber joists & 22mm T&G chipboard under click vinyl tiles: https://www.kingspan.com/gb/en/knowledge-articles/a-guide-to-constructing-a-floating-floor/ But replacing PIR with Jabfloor EPS (3 x 100mm)

Perhaps jablite 300mm Was thinking of levelling compound, the sort that allow 3mm thickness upwards. Unwise?

Small unheated extension, a kind of porch. Floor plan dimensions 1400x 3200 mm. Floor level to be raised from concrete sub base up to adjoining internal floor. Height difference 325mm Intended: Click vinyl tiles atop 25mm levelling compound on second DPM & 100mm floor insulation. Beneath insulation, about 20mm sand blinding. Q How to make up the remaining approx 175mm under the sand? Least costly option preferred.

MVHR compulsory if you have excellent airtightness (in practice, likely to be compulsory if you achieve 2 m3/m2.h@50Pa) If your house remains leakier than that, consider Vent Axia Tempra heat exchange fans to replace your existing extractor fans. Background mechanical ventilation without the expensive retrofit of ducts etc

43 kWh/m2/yr with Airtightness 3.75 m3/m2.h@50 Pascals Just an example from real data 75% of that on space heating. Rest on water heating.

3.75 m3/m2/h Target for SAP pass was 4. Phew Started at 4.6, leaky trickle vents were main culprits. Some sockets on first floor stud walls too, because polythene membrane not put under rafters & roof membrane highly permeable. (Will have to put bungs in the unused sockets on cold days). Was on floor by kitchen units shoving in the foam bits even as the test was on. Some air flow perceptible there. Extractor fan plastic seals - some had come undone during test, but sealing them up would probably have taken score below 3 (with risk of expensive MVHR requirement) All in all, relieved.

Time short, clever solutions difficult to attempt at short notice. So, cheated. Blobs of expanding foam cut into strips, reached under the units and pushed them into gap between plasterboard and screed. Not 5 star work, but if there were gaps before then they are at least less "open" now. Let's see how the test goes. Thanks for all the ideas.

airtight membrane joined with orcon airtight adhesive sounds like a possibility. At worst, seal top of base boards with that and silicone seal from bottom of baseboard to floor? Perhaps easier than reaching across the 600mm to the wall, under the units. Airtight membrane with orcon was what went under one problem bath, sealing pb to floor. Feasible but not enjoyable experience.

Belt and braces. No parge, but Celcon blocks (negligible air permeability) and 5:1 mortar well pointed, all sitting on near-raft concrete foundations which in turn rest on hard brash. In short, very little likelihood of movement. Plus joist ends on first floor have tony tray.

yes

Airtightness test people coming on Tuesday. Plasterboard to floor sealed everywhere except behind kitchen units. How to mitigate? Something to seal above and below kitchen unit baseboards. (Pls assume that for various reasons mitigation is needed) Something not too demanding time wise.

What draught excluder strips work around loft hatch and other openings? Preparing for airtightness test

Yes, the problem circuit in the kitchen was connected to the porch thermostat in error. Sorted, the kitchen (3 circuits) all now cut out at the desired temperature. But new problem uncovered: porch UFH stays cold no matter what. Can feel it with back of hand, stone cold. Set the porch thermostat to 18.5C but the porch temperature remained at 15.5 no matter what. Even with the water mix temperature for UFH turned up from under 40C to over 50 C.

100mm Celotex 50mm liquid screed Flow temp was 50c Turned flow temp down to 35c, kitchen zone stayed at 21c with thermostat set to 22c Now flow t set to 40 to check response

Hetta system

New build in progress, UFH 4 zones, the kitchen/family room zone has 3 circuits. Set thermostats to 21c. Kitchen/family room went to 24c. One of the 3 kitchen circuits stayed warm constantly. Why? Electrician says no problem with the thermostats or connections. How to solve?

How to seal skirting board to click vinyl flooring (expands and contracts with underfloor heating)? Sealant? Expanding tape? Other?

Putting in a couple of these near ceiling to take boxing that will support a 4 inch extractor fan & ducting Wall is Celcon aircrete (high strength) with plasterboard on dabs. Q. What screws would do? PS Tempted to try plasterboard foam adhesive for the bracket & the boxing, without any screws

Need to check if it is really between panes or just on the external surface of outer pane

New build in progress. Moisture between panes condensing on outer pane. Defect or just normal?

Yes, that's the plan

Good idea but not enough access. Will probably try "caulking" the wall/ceiling junction from below with Acryrub SWS

Riveted

Good job. Polyfilla? or similar?

Only for some. Mostly 400mm loft insulation roll covering everything.