Not unless the house is listed

Depends where you live, but I'd go for 100-120mm in the UK. I'm not sure about R-value (i could calculate after some research), but to give you an idea. My friends in Cardiff, insulated the house with 100mm polystyrene panels. Before insulating, on a typical winter day wit ext. temp around 0C, when they switched off boiler in the evening, in 8h by the morning the temp inside would drop from 20C to 15C. Now after insulation the same exercise gives results from 20C down to 18.5C. A lot of depends on what type of wall you have and how much thermal mass is there, but this exercise is very simple to estimate how much savings you can get.

The principles will be the same, but instead of adhesive fixing, you will be using only mechanical once, fixing the panels to your T-111 planks (or even deeper, to the wall). I would clear the wood prior insulation works and treat it with something anti-decay to last longer. Alternatively just remove the planks as they will be totally redundant and they only limit durability of the system.

@@mateo_dequ To clarify…do you mean, 1) remove the old siding (& wrap, it it exists), 2) fir-out the studs to fit thicker insulation, then 3) wrap & new siding on it? Have thot about that, too…. It makes sense. But, if I went to that effort, I’d remove the old, saggy mingy batts & replace all of it-which could probly measurably improve the insulation of the walls.

@@Chimonger1 what type of wall do you have behind the siding? is it a brick? i would remove the siding mainly to avoid decay. The condensation should n't appear, but if there are frosty winters with -10C, a bit of condensation could potentialy happen between insulation and wall and your siding would get wet. If you have a brick wall, i would remove siding, clean the wall and follow the instructions in this video. I don't think having siding on top insulation is a good idea because you will have to use more stud fixings and for siding I think it would have to be steel studs which would impose heat loses . I am a bridge ingineer so not that familiar with housing stuff but I'm not sure if there are any strong plastic studs to fix your siding therough 100mm insulation down to the wall (approx 180mm long). Lots of drilling, time and costs. You'd be better of with the standard finish as presented on this video.

@@mateo_dequ No bricks here, except in the crumbling chimney. It’s an average, code-cheating 2”x4” stick frame, 1970s tract house. Climate is kinda coastal, in WA State, US. T-111 plywood siding. We get temperate humidity…but less now. We seem to have lost our very wet winters; WA has been turning into “CA-North”, for the past 30 years. Summers have become hotter, drier, as FEMA reps try to convince public that small towns full of old wood houses haven’t any fuel to feed wildfires 😳!? & weather forecasters on news, hype the slightest hint of rain as-if it will be a deluge🙄 Winters can drop to single digit F., but generally spend maybe a couple weeks per winter, down in the 20’s or teens Fahrenheit. In the last 23 years, we’ve had maybe a handful of winter temps in single-digit F. Alaska gets colder, & folks there have been retrofitting, too. A paper read decades ago, described what they did in Alaska, adding insulation right over the old siding of stick-built houses (hard to imagine houses there with 2x4 frame, & such thin insulation!!, but chintzy tract house building went there, too. The paper addressed the mess that could be caused, if the new stuff was too thin. It could cause a dew-point inside the old wall if not enuf was used on outside-very bad. To prevent that, they figured: Figure total R-value desired. Put 3/4 of that total on the outside. That should leave the old stuff well protected, & prevent any dew point in wall. They get much colder, much longer, there. So… …if our existing insulation is approx. R-10, & I want a total of R-30, I’d need to put about R-22 on the outside, according to Siri’s math. That’s About a generous 3/4 of the total on outside, leaving old wall intact. One company (Outsulation) got in trouble, gluing insulation panels to old wall cover, then sticking on new siding…they did not use enuf outsulating to prevent a dew point in the old wall, so houses got rot-within only a couple years….it was a huge, costly mess. Others install a drip layer, or a thin airspace, or a breathable wrap, before adding the exterior insulation….have not found anyone complaining about those tactics…so far…& have seen a commercial near here being exterior-insulated, by just gluing a couple layers of 2” thick foam panels on the outside…I think they’d wrapped the outside 1st. Average 2” thick closed-cell foam panels are R-10. Special order @ a big box store, might still get a different foam between 2 layers of heavy reflective foil, we’re R-13. But everything is now such Gonzo profiteering prices, our exterior insulation project is on-hold. Prices here are insane!

how do u pronounce ratio