Superinsulation -- the Process

The Exterior Insulation Retrofit

The front of our house -- "before"

Here are the steps we took to make our exterior insulated retrofit.  

1. We replaced the bathroom window.  This was the only window which we hadn't replaced, it was a single-paned window with metal casing.  We got the latest, greatest, R-9 (!) glass for the window, which was probably more insulation value than was in our walls.

New bathroom window

We were both delighted and chagrined to find out about the R-9 glass.  We had previously replaced all our other windows (over many years) with standard double-paned low-E glass, which is probably about R-4 (not that bad compared with what we had before).  The R-9 glass has some special gas in between the panes.  If we had known this at the time, we could have had all our windows brought up to R-9, but we couldn't justify the additional cost at this stage to do them again.  Just something to keep in mind as you plan your own project, in case you've got the money or haven't replaced your windows to begin with.

2. We got a heat-recovery ventilator.  Because our house was going to be sealed only slightly tighter than Fort Knox, we wanted to be able to get fresh air.  Such an air exchanger means you will lose a marginal amount of heat, but not quite as much as you would lose by just cracking the window to get fresh air.  

The Heat Recovery ventilator, seen from the basement

3. Dig out the area around the house to put in below-grade insulation.  We put in 2" thick polyisocyanurate all around the edge of the house. 

Excavating around the house

Just before putting in the polyiso

Ditch refilled, with polyiso inserted

4. Horizontal boards 2.5" thick were put all around the side of the house (to support the polyiso insulation).

Step 1, put bolts in the side of the house

Step 2, put up boards.  Note also we decided at this point to repour the front porch steps and replace the supporting poles (not part of the insulation per se). 

5. Add horizontal sheets of polyisocyanurate sheets 2.5" thick. Polyisocyanurate seemed like the best choice, with R-value of 6.5 per inch. 

After putting in the horizontal polyiso sheets

6. Add vertical boards 2.5" thick to support vertical polyiso.

Vertical boards are put in to support vertical polyiso sheets

7. Add vertical sheets of polyiso 2.5" thick.

After installing vertical polyiso sheets

8. Add plywood sheathing over the whole thing. 

After plywood sheathing is added

9. Flashing is added around doors and windows.  I am told that you really need to do this step right so that moisture does not get in behind the exterior and rot what you have added from the inside.  Also, we added new supporting posts or pillars for the front porch that were thicker and more aesthetically pleasing than the old slender poles would have been.  

After flashing added

Notice, also, that the exterior insulation does not come all the way down to the ground.  You can't really tell from the street, but there is about 1/2 inch between the ground and the bottom of the new insulation.  This is because of a Denver building code regulation and is required to insure proper drainage.  You lose a small bit of insulating value this way, though this effect is probably quite small.

10. Add Jumbo-Tex and wire mesh in preparation for the stucco.  We decided to do stucco rather than vinyl, which was slightly more expensive, but gave us the look we wanted.  Actually, we would have really preferred the original brick, but to add brick to the outside -- even the "thin brick" now being advertised -- would have added about $10,000 to the project.  This project was already quite expensive and we didn't want to make it any more so. 

After Jumbo-Tex

After wire mesh

11. Added stucco.

After stucco

12. Added the color to the stucco.  We chose an off-white for the base color, snow white for the trim, and blue for the accent around the doors (and also the fascia). 

After color added

13. Replaced the roof.  This wasn't part of the insulation process, but we discovered that our roof needed replacing in the course of the project -- we also completely replaced the gutters as well.

New roof

14. We also got solar power at the same time, and this gives a view from the rear of the house. 

Solar power and back yard

15. Finishing up: reattached the house numbers, mail box, etc.

With all items re-attached to exterior

We will update you on the results.  It is clear that this has had a significant effect on the heat requirements, cutting it more than 50%, but we don't yet know how much, we'll have a better idea by April or May once the coldest part of the year has passed.