February 19, 2020

95% of the polyiso insulation foam boards arrive on site. The supply house discovered that they didn’t have enough 3” thick boards to deliver so they are going to deliver the remaining ones the week after.

In most design and construction sequences insulation is installed wherever there is space left in the wall cavities after all the structural, mechanical, electrical, and plumbing stuff goes in. As a result, only a fraction of those walls have insulation that performs at the level stated on the home's marketing sheet.

We want the real-world performance to match those on paper. That means putting the MEPs inboard of the insulation layer, having layers of continuous insulation that cover even the studs, and using construction techniques like SIP to minimize the framing factor (minimize the amount of studs/wood) in a wall to allow more room for insulation.

Yes this is a lot of insulation for a house that is only 22' x 8.5'. But it is the amount needed to reach the high levels of energy efficiencies in order to come close to meeting the passive house standard and going beyond the net zero energy standards.

The goal is zero cold and hot spots in the tiny house even right next to the wall, windows, and door all year long.

February 20, 2020

They say in life nothing goes perfectly as planned. Construction is even more so. The day before I was told the delivery window would be from 1 to 3pm. Ok, that gives me a good number of hours after working graveyard to sleep before waking up to be construction manager. 9:30am I get a call from the delivery driver saying he is 20 mins from arriving. Ok, roll out of bed and tell the brain to wake up and stop feeling like crap.

Once outside with the clear sky sun on my face I start feeling better. Open the garage to take out a few remaining items out of the planned staging area for the wood. Go around the corner of the block to see if the delivery truck has arrived. See a truck at the far end of the block stopped. Walk down to find the driver confused looking at the mismatch between the house number and the number on his paperwork. Do they not use Google Maps?

Delivery driver manages to get both loads off the truck and I see that none of the plastic sheets that will be used to make the belly pan aka splash guard, slash trailer bottom waterproofing. The day before I called and was told those plastic sheets would be added to the lumber delivery and that I would be refunded the delivery charge for the plastic panels. Those panels were not on the pallet inventory sheets either. Note (1) to self, will need to call and track down what happened to the plastic panels.

Driver leaves and my family and I get to work moving the lumber into the storage area in the garage. Note (2) the quality of delivered lumber is overall noticeably better than the same lumber on store shelves. Reasons are multiple, people pick out the good pieces and leave the bad ones still on the shelf, and people buy extra, they get beaten up in transit and on the jobsite and the remaining unused material gets returned and put back on the shelf.

As the lumber gets moved and organized, I'm also counting to make sure the right quantities got delivered. Guess what? Note (3) Home Depot people can't always count. I ordered 8 2"x4"x8' pressure treated and only 7 were packed, and ordered 68 sheets of OSB and 72 were packed!

I ordered 68 sheets of OSB because at 68 sheets the price per sheet drops down from almost $20 per sheet to $15. Places do this because of the labor savings from buying who pallets. However in this case the pallet comes from the factory with 64 sheets per pallet so I don't know why the price drop didn't occur at 64 sheets. Likely a computer programming typo. I actually only need 60 sheets but 60x20=$1200 but 68x15=$1020 so what would you do in this situation? Note (4) sometimes ordering more than you need cost less than ordering the right amount. And lastly Note (5) plan on fork lifts damaging something. Damaged sheets of OSB can be used where a cut down narrow sheet is needed.

March 9, 2020

Last week the 3” pieces of polyiso insulation boards for the sub-subfloor were cut to size and test fitted. The plastic panels that serve as splash guard material were also cut to size, taped together, and the perimeter seams taped to the trailer bottom. Three inch wide ZIP tape was selected for all construction taping needs on this build. The lower most layer of polyiso were cut such that the seams rested on the center of the trailer’s steel cross members to ensure they are fully supported. Liquid Nails Fiberglass Reinforced Panel (FRP) Adhesive was used to glue the plastic panels to the bottom most layer of polyiso. I’m not sure if this adhesive was necessary at all. My thought was that the plastic panels would add some tensile strength to the bottom most layer of polyiso however, there isn’t much tensile loads happening at all. The forces experienced will all be vertical compressive loads.

Today the two layers of 3” polyiso were glued together using Great Stuff Pro Wall And Floor Adhesive and clamped down. I purchased all of the Bessey 12 in. Clutch Style Bar Clamps available at my local Home Depot as well as utilized every single suitable clamp I had in the garage. All adhesives require the work pieces to be pressed together for the adhesive to be effective. Great Stuff Pro Wall And Floor Adhesive is a moisture curing adhesive. I was not confident that moisture in the air can get to the center of insulation boards that are almost 4x8’ in size. Thus, I used a spray bottle of water put a little bit of moisture onto the insulation boards before pressing them together.

The 3” polyiso insulation boards presented an unexpected construction challenge. They arrived in two separate shipments. The first shipment delivered 4 of the 11 pieces and those 3” insulation boards were actually 3.2” thick. The second shipment of 3” insulation board were actually 2.8” thick. I did not expect such large dimensional variations between batches of polyiso insulation boards. In fact polyiso manufactures list thicknesses in increments of 0.1” as available for order. I.e. one can order a 2.8” and a 2.9” thick insulation board. This specification precision lead me to believe that if I ordered 3” insulation boards, I would get insulation boards that are really close to 3” and not varying by 0.4” in thickness! I’ll reach out to the insulation manufacturer, Carlisle, to see what they have to say about this issue. Sheets of 7/16” OSB were used to solve the 0.4” in elevation difference between the two batches of insulation.

Best Way to Cut Polyiso Insulation Boards:

I tested a number of different ways to make clean accurate cuts on polyiso insulation boards. The best way I found is to use a track saw with the speed setting turned down to the lowest setting.

March 12th, 2020

A lot of progress happened in the last two days on the beyond net-zero energy tiny house. Now all of the sub-subfloor and subfloor polyiso insulation has been cut and tested for fit. Almost all of the first layer of osb for the subfloor has been cut.

The next steps are to (1) cut channels in the insulation boards and the subfloor to accommodate drain, waste, and ventilation (DWV) pipes for the shower and sink then back filling with spray foam to encapsulate the drain pipes and (2) glue down the polyiso and osb boards.

The floor has R57 in insulation! In comparison, new homes built today have R30 but if you factor in the thermal bridging from the floor joists, it is more like R21 in performance.

Thanks to my family members for giving me a hand.

March 20th, 2020

Here is a picture of the amount of low-rise spray foam adhesive used to glue each piece of polyiso to polyiso, polyiso to OSB, and OSB to OSB. The pieces are glued then clamped down until the glue dries. Since the adhesive uses moisture to cure, a fine mist of water is sprayed onto one of the faces to facilitate curing.