No Housewrap – No Problem. The New Way of Weatherproofing Homes During Construction.

By Lance Manlove, in new homes

enviro-driWe build homes in a coastal environment very near the ocean which means wind and wind driven rain.  With the wind comes difficulties keeping the house wrap in place and in good condition during the framing and mechanical phases.

The typical tapes and fastening techniques used to hold down the weather resistance barrier are not very effective in cold weather and windy conditions.  This leaves the exterior vulnerable to future leaks, water intrusion, rot, and decreased thermal performance of the insulation due to air infiltration.  See picture of probable installations.  There are other products on the market that have the weather resistant barrier laminated to the OSB exterior sheathing.  This eliminates the poorly installed weather resistant barrier and the material getting ripped due to wind but the system is purely relying on a single layer of tape to prevent water from getting behind windows and doors.  Also, any nail holes through the sheathing in this system are not covered or sealed in any way.

I have been looking for quite some time and even did some R&D on a system that can be applied over sheathing either in roll or spray form.  At the IBS 2014, I found EnviroDri produced by Tremco.  We currently use Tremco Watch Dog as our foundation waterproofing system of choice so when the same company released a liquid applied WRB I was excited to give it a try.

What are the advantages of the EnviroDri product?

1.       It is liquid applied after the framing is complete and the sheathing is attached so all the nail holes are covered/sealed by the membrane
2.       The membrane at 20mils thick has a perm of about 12.  This allow for drying to the outside of the wall cavity in the event water ever reaches that point.
3.       All the horizontal and vertical seams of the sheathing are sealed with the membrane and taped with a tape mesh.  This is very similar to how drywall tape is sealed over the seams.
4.       The windows are liquid flashed in place to mitigate any water intrusion and a counter flashing is installed over the head flange for added redundancy of water protection.
5.       All penetrations and flashings are sealed and covered with the membrane even the sill plate.
6.       The house is being air sealed the same time it is being weather sealed.  This will reduce air infiltration and the air changes per hour which in turn will benefit the home owner with better energy bills.

The product was applied by either a spray system or roll on system – both worked equally as well.  If there is a breeze on the location the rolling may be a better option as this will reduce any chance for over spray.  It dries to the touch in about 30-40 mins depending on the temp and humidity when applied but the working time of the product was great.  Once it was cured overnight windows and doors can be set.  I really liked the application of the product and the first phase of weather protection on the house.

I will write part 2 of this blog once we have installed the windows and installed the membrane flashing. Stay tuned!