Heat Recovery Ventilator

Heat Recovery Ventilators are mechanical building components that serve several important functions for newly constructed, tight buildings.

As a quick attempt to summarize HRVs in writing, in air tight houses, it's important to have sufficient fresh air to breath. If there is not sufficient fresh air, the indoor air will eventually become stale, and increasingly full of carbon dioxide from human expiration and from residual toxins that are embedded in building materials that are used in the construction.

Air leaking through walls is an expression of the second law of thermodynamics

Mechanical ventilation is used to promote circulation of fresh air around the house. An HRV not only circulates fresh air, but balances air and vapor pressure inside and outside the house, mitigating the tendency for air or moisture to drive through a wall assembly.

This tendency is due to entropy (aka. the second law of thermodynamics), or the fact that high pressure systems migrate pressure towards low pressure systems. By reducing the difference between the air pressure inside the house and outside the house, there's less incentive for air to leak through the walls to equilibrate on either side of the wall assembly. When air and moisture pressure is equal on either side of a wall, less air will leak through the wall. This leak reduction, in turn, creates a more durable wall assembly over time. In addition to balancing pressure, HRV's also "recover heat" by passing the incoming and outgoing air through an aluminum core heat exchange where the conditioned air's heat is transferred to the incoming, unconditioned air.

My verbal explanations for the HRV in the attached videos are convoluted. The 2nd video explanation is a little better, but it's still a little bit technical. Anyhow, here's a video of the Fantech 1405R HRV upon its initial installation.



Here's a video of it now that the HRV has been fully installed.

Mosaics and Tiling in the Bathroom

Tiling the bathroom has been Deb's main focus in the ADU for the last month. All her work has paid off; the bathroom is one of the loveliest looking spaces in the ADU now that its wall have been designed so skillfully. Deb chose an Oregon mountain scene as her inspiration: one wall in night, and one wall in daylight.

Here's time sequence pictures of the wonderful mosaic being installed. 


We used a double-sided self adhesive tape product called Simplemat to stick the actual tiles to the wall. Historically, a cement product called "thinset" has been used to adhere the tiles to the bathroom wall, but this sticky product makes the mosaic process much easier.

Once Deb has laid out the mosaic tiles, she covered the tiles in grout. Then, she cleaned and scrubbed the grout. Once the grout has fully dried (after 72 hours), we'll put a sealant on the walls and then they'll be complete. Here's a video that shows the grouting process in action.



I showed off the tiling for the bathroom floor in earlier posts. Here's a picture of the finished bathroom floor, now that the toilet has been installed.

We have a couple more tiling projects left to do in the bathroom and kitchen. And, because we like the look of the look of tile so much, we've decided to use it on the stair risers as well. Here are some pictures of tiles being used on stair risers, so you can see this approach in action.

The Home Stretch and More Miscellaneous Fun Finish Work Projects

There's so many finish projects happening all at once. We're expecting to have our final plumbing on Monday, and then have our certificate of occupancy inspection later this week.

This video is showing off some more finish details; it features a custom made blue pine door, the finish lighting work, the water heater, and the gas meter hookup.

Granite Countertops and More Miscellaneous Fun Finish Work Projects

Last week, the granite fabricator came and templated the kitchen countertop space above the empty kitchen cabinets so that they could cut and shape a granite slab at their facility. They used the template to cut a piece of tan-brown granite to size. When the granite arrived, the still had to cut out a piece of granite for the sink, which they did on-site.





With the granite installed and the appliances here, we're ready for the finish plumbing, which will start on Monday. Finish plumbing involves installing the kitchen appliances, sinks, and the water heater.

Here's a few other projects that we've been working on in the last couple days, including another Blue Pine ceiling installation. Blue Pine is actually Ponderosa Pine that has had a fungus do some damage to it, which results in a blueish tint. We've also been working on the stair treads, tiling, and much more. Here's a quick video update.

Miscellaneous Fun Finish Work Projects

The "finish work" is all the stuff you actually see when the buidling project is done. For the last few weeks, and until we finish, everything we do is "finish work". This five minute video showcases some of the projects that we're currently working on. 

Installing the Cabinets

I'm pulling some very long days right now in the ADU to get the job done before my September 1st (hopeful) move-in date.

Last week, I was working primarily on cabinet installation. My builder has been finishing up the siding work, installing reclaimed doors, working on exterior trim, and building stair treads.

I'll have a post dedicated to the stairs, which along with the bannister/guardrail, will be a prominent design element. The stairs are turning out very nicely, and I'm excited to see what we come up in the end for both the main stairs as well alternating tread stairs to the attic. 

Here are some videos of this cabinet installation process, starting with a quick video during their arrival.



We started by installing the wall cabinets. We installed the upper cabinets first- they take more time than installing the base cabinets.



Here's a video of the appliances arriving. I installed the base cabinets before the appliances arrived.



Then, the granite fabricator's templater arrived and took measurements for a granite countertop that they'll install next week.

Here's a video of the current status of the cabinets, including a surprise cabinet installation in the bedroom.

Staining the Concrete Floor

I had read about staining a concrete floor, and learned that cleaning it was the important step before staining it.

Accordingly, I swept it, scraped the concrete with a knife, and then vaccuumed up the piles of dirt that were left behind from framing, drywalling and painting.

I mopped once, and the floor looked dirtier than it did before I started. After seeing how dirty the floor was, I figured that I had better do a much better job the second time. I mopped it again a second time. It looked cleaner, but there were still massive mop streaks and arcs of of dirt left behind.

Earlier that day, I had inquired about having the concrete company return to plug in the divits that are left behind by the blossoms from the cherry trees. They were able to come the next day, but said that the concrete would take a week to cure. Unfortunately, the project schedule demanded that I have the concrete stained right away---we can't install cabinets until the concrete floors are stained. And we can't have the final plumbing done until the cabinets are installed and the counter-tops put into place to hold the sink.

So, after mopping a second time, I got down on my knees and carefully scraped the floor with a razor blade, un-caking minute layers of dust and grime. Then, I mopped it again and vacuumed up the water with a shop-vac.

Then, I got on my hands and knees with a sponge and scrubbed every inch of the concrete.

In the morning, cleaned once again, and the proceeded with the staining. Here's a video the staining process.



After two layers of stain throughout the day, on the following day, I sealed the floor, and now will let it dry and cure for 72 hours. I think it's going to turn out very well.

Update: Here's a few pictures of the floor after the sealing.

Flooring and Tiling (Continued)

The flooring has taken about 30 man hours to do so far, and we're about 3 hours from being done. We used reused flooring, so it was slightly harder than using new flooring. We have laid approximately 500 sq ft.

I've been doing this with my father, who has been cutting the wood pieces to length. Meanwhile, I've been installing the pieces.

Deb has been doing the tiling. She says that the process so far has taken about 24 hours. But, as you can see, she's included a lot of artistic flare, using many smaller tiles, which takes much longer than a conventional tile job.