"Out"sulation project
 

As part of my seemingly forever quest to reduce my heat load, I am now starting to skin the outside of the brick house. Here are a few pics as I start. Note where the window and door is......I built window boxes a few years ago knowing I was going to do this so the windows actually sit outside of the current house.

I ordered, what i thought was a 20 lb PUR foam from Germany for a manufacturing project and due to some miscommunication i got 100m2 of a 3lb foam equivalent in a 40mm x 1mx2m size. No good for the shop, great for the house. R value is supposed to be quite high.

I will next put 2x2s vertically after placing insulation between the strapping so there is very low thermal bridging.

Great to see this project. I am wanting to do the same thing to my house... eventually. I'm anxious to see how you handle certain things. How much foam are you putting on the outside?

80mm or 3" give or take. The first pieces go between the 2x2s as shown then I will put more 2x2s vertically and put tyvek and Hardypanel or wood siding on it.

Are you familiar with the "rain screen" concept?

Sounds pretty much like what you are doing. If you are unfamiliar, there are some fine points that you might benefit from.

-AC

yup, that is probably what I will do. 3/4" gap between the tyvek and the siding so liquid can run down and dry naturally. The only question comes with the use of foam because from what I have seen most people are putting ROXUL or another drainage board on the wall AND the insulation is over a stud wall while this is over brick.

I haven't put a rain screen system on my house (yet). But I have a friend who has put one on his house... your 3/4" space seems a bit large to me, I believe my friend was using 3/8" space, but it probably doesn't matter.

I have noticed that here in Portland, where winter rain is a big event, there are many, many examples of new construction that are using this technique... especially houses and buildings designed by architects. Builder designed houses and renovating companies don't seem to be getting involved.

On the building science website, there is a report on a 20-year-later tear off and assessment of a rain screened building, and there was essentially no problem found with the approach.

But one of the fine points I was referring to is insect intrusion, and the care that needs to be taken to provide air flow entry and at the same time prohibit insect entry.

-AC

Very good point about the insect screen....

Here is the progression. The first layer of insulation is on between the 2x2s on the lower area. I cut the insulation with a table saw.

And the next layer of foam will be solid, no strapping between sheets, right? The strapping will sandwich the outer layer?

You can see vertical 2x2s. They will have the same insulation between them for a total of 80mm (3"+). All the literature I have seen (in German) puts this insulation at around an R9/inch but it is not available here. Even if it will be at least R6/inch, I would be happy with that. It is raining here for the next couple of days so no update till Wednesday at least.