Spreadsheetman

50mm of PIR then plasterboard will probably drop the u value from a bit over 3 (if it really is un-insulated) to 0.38. That would make a big difference and only lose 65mm or so.

My new place is on oil (boiler is almost new too) so I can’t run very low flow temperatures. What I have done is design for 70deg flow, 50deg return (60deg average at rads) so the boiler will properly condense. I have made all new or replacement rads k1 type and not allowed for the insulation improvements I am making so there will be a good margin. If later I switch (or am forced to switch) to an ASHP then rads can be replaced with k2s to accommodate a lower flow temp. I am in the fortunate position of being able to replace all heating pipework though and replace most rads as we are eliminating all pipes in the concrete floors downstairs as part of the renovation process.

I built my own spreadsheet (similar to the one that gets posted on the forum quite often). I have also used Stelrad Stars, but it is inflexible as you say (and there are obvious missing features like the ability to duplicate a design). Good for coming up with a quick menu of rad choices though and was a useful sanity check for my own calculations. For the house I bought recently an analysis showed me that adding insulation into the cavities was the big win. That saves 15% of energy at a stroke for a relatively small cost. Other stuff makes much less difference, but I’m making quite a few other improvements as a consequence of solving other problems. Actually I think the CWI will make an even bigger saving in practice as I have closed up a vent hole through the cavity (old boiler air intake) and there was a considerable draft in there even when the outer brickwork was replaced so there is a lot of cold air movement round the cavity. There are no deliberate air bricks or vents, so I think it is mostly down to the open cavity tops at the front of the house that I will be closing up.

My condolences. I lived in a 1930s semi with solid walls for many years and the only saving grace was the living rooms and (used) bedrooms were on the party wall so inherently warmer. Really doing anything serious about the heat losses would have been so expensive and disruptive that I just couldn’t bear to do it. Have you done a room-by-room heat loss analysis of the property?

My go-to large hole bodging technique is to use lightweight block and cut to fit with a block saw. Then mortar it in. Add a bit of foam sparingly at the end to seal the remaining gaps.

My chalet also had 2 sloping roof dormers at the front in the bedrooms and a single small dormer at the rear which was the bathroom. It was extended in 2009 by building the entire back wall up and fitting a shallower pitch rear roof. This added full-height rooms across the entire rear of the house so an en-suite and a large walk-in wardrobe were added. The revised roof was supported with a large beam just above ceiling joist level supported at the ends on the eves walls with a central vertical support steel (hidden in a stud wall) transferring some of the load down to an internal load-bearing wall. I thought it was a very good solution to some of the inherent issues of the chalet upstairs layout. I also have eaves with dead space at the front, but mine are quite small so not worth trying to create storage in there.

Is that built under permitted development? (Or whatever applies outside England)

Do you have cavity walls and did you see if there were insulated cavity closers to the sides of the window when they were fitted? I recently had a couple of windows replaced in my 70s chalet and the window reveals were solid block bridging the cavity sides and below. I.e. a big cold bridge. These blocks had to be cut out and insulated closers fitted before fitting the windows.

Ok, so arrived at a solution. Bought some samples on eBay so I could try the ideas out. Had a false start with a Knauf product (rocksilk flexible slab - very floppy and crumbly, falls apart when I tried to pick a slab up - useless), but success with Rockwool RWA45 which is easy to get and relatively inexpensive. The density of the product is key, RWA45 is 45kg/m3 so there is more meat to it and the slabs self-support, but are still flexible. Cut to fit between studs (2cm oversize on approx 400mm spacing) it stays in place and the next layer can be held behind the studs with plastic insulation support mesh stood off with big plastic washers (60mm) and long drywall screws. I’m doing 75mm between studs and a continuous layer of 100mm behind. No PIR board in this solution, so a lot quicker to fit and the batts cut up easily with an old handsaw. Ubakus says u=0.206 which is great. (in context of the rest of the fabric) I had a bit of a result; when the downstairs ceilings came out I could get at the back of the dwarf walls from below so didn’t have to take them out. I can insulate the ceiling between the 175mm joists from below using the same stuff (with small rigid PIR sections to make sure the cavity between joists and floor-ceiling is completely closed even if the rockwool settles or shifts). My late 70s chalet was quite advanced for the time as they had stuck a load of fibreglass behind the dwarf walls and in the corresponding floor-ceiling gaps below. That didn’t fall down with the ceilings as I expected, but I had to pull it all out anyway to get access for plumbing and electrics.

I’m getting CWI (carbon coated bonded beads) added soon to my 70s chalet, but some of the cavity tops are open so I was thinking of closing them off while I do other work in those areas. I have had a look online and there appear to be a couple of types of closer available - cavity socks (which appear to be rockwool in a bag) and plastic laths with EPS/XPS stuck on. Both of those are inconvenient sizes (65mm cavities) and generally have to be bought in batches of way more than I need. I will have a load of rockwool offcuts (rwa45 slabs in 75mm and 100mm) left over from insulating elsewhere so I was thinking of making my own closers by wrapping rockwool sections in plastic netting to keep any bits together (and make it easy to pull the closer out if ever needed). (the netting is also left over spare) Does this sound like a workable plan using stuff I already have?

I like that wood flooring on the landing - what is it?

Interesting topic since I need to get the cavities insulated on the 70’s house I recently bought. The main incoming feed cables from meter to consumer unit run in the cavity, so I didn’t think eps bead was an option due to the pvc insulation issues.

Good topic. I’d like LVT in the kitchen, but my wife wants tiles. Side question - In my case it’s an uninsulated concrete slab; is it worth putting one of the 10mm (or less) insulating tile backer boards down first, or will it make so little difference in practice that it isn’t worth it?

I’ve got an insulation job coming up where I will need to stick a load of PIR board between floor joists and stud wall battens. Board will be a friction-fit to some extent, but I need to seal round the edges and prevent it slipping. Also I have various drafty gaps to fill where electrical cables and pipes penetrate blockwork. I was planning to use gun foam products, but can I get away with just one type? e.g. Soudall Soudafoam window&door SWS foam - can I use this to do both jobs?

You need an air gap between the top of the insulation and boarding to avoid damp issues. Look at Loftzone Storefloor as a relatively easy solution. They do two versions of the standoffs to suit different insulation depths. As long is the old insulation is in decent condition then I think the majority of people just insulate over the top. If the first layer of insulation is running between the joists, run the next layer at 90 degrees to the joists. Wear a good dust mask!

I’ve got a fiddly insulation job to do to a dwarf stud wall where I can only fit the insulation from the front. Wall is about 1.2m high and made of 75mm x 50mm timber with uprights spaced 400mm apart. There is a space vented to the outside behind the wall. My current thinking is to use 75mm rockwool batts vertically behind the studs held in place with a run of plastering galvanised metal mesh laths (2ft wide) stood off with 90mm plasterboard screws and big washers. I can get in above and below the mesh to fit the screws since it doesn’t run full height of the studwork. Once the rockwool is in place I will then fit 75mm PIR board between the wall uprights and plasterboard over the front. Should give u around 0.21 which is fine for this application. Question is which one of the many types and makes of rockwool batts to use? It needs to be stiff enough to remain in contact with the back of the studs when the ends are not supported (2ft mesh leaves about 300mm top and bottom unsupported), but not so stiff that it can’t be stuffed in through the studwork frame.

Back at my old business premises it took 3 attempts to fit a smart meter. The first guy turned up with a single phase meter then the second one turned up with a 125A max meter, but we had a bigger supply. There was a long gap before the 3rd attempt, presumably until their industrial team that really knew what they were doing had a slot available. Whole process took over a year if I remember correctly.

I’ve been doing a “how it works” investigation in the house I have just bought and have found a prime bodge in the en-suite. There is an extractor fan in the ceiling discharging into an insulated flexible duct in the loft. I’d not spotted an outlet anywhere so went looking today and lo and behold, no outlet, the duct was just open to the loft space. It appears that the duct was a little too short and whoever was installing gave up without drilling the gable wall for an outlet and extending the duct. I’m going to sort it with a couple of metres extra duct and I thought to use (say) 200mm of 100mm plastic pipe as a joiner with a couple of jubilee clips to connect the inners, overlap the insulation (25mm glass fibre), pull the outers together and wrap with aluminium tape. Does that sound workable, or is there a more correct way of doing it? (Fortunately the extract fan is broken and the en-suite was hardly ever used, so no damage done in the loft)

Yes, exactly - de-list and flatten is the only thing that makes any kind of sense for wrecks like that.

It’s surprisingly unstinky. We’ve got a big 3-property Klargester bio disk plant at our cottage and I help with hosing it down with water when it is pumped out with the lid up. It’s not bad at all.

Lol. Listed buildings and conservation areas are one of my hobby horses. It’s yet another example of how backward-looking this country can be. I’d keep the very best, de-list the rest and make it easier to demolish and replace with sympathetically designed efficient modern buildings.

It’s powering some kind of usb-charged water pick thing in one of the pics. I’m contemplating one of those dual toothbrush charger points for a bathroom, but also thinking that a dual shaver socket and a shelf may be less likely to go wrong. (The toothbrush thing is also a landscape format hole, so can’t just drop a standard shaver point in if it proves unreliable)

Quite the opposite. I did some ballpark numbers for the house that I am in the progress of buying and air changes were about 50% of the fabric loss assuming I can get them under 2, which is optimistic.

Yes, could well be Artex, but it’s very hard to know by just looking at it. I’d have a sample taken and tested so you know what you are dealing with.

Can you recommend particular full-bore valves? Any have compact actuators, or are they all large levers?