Seattle Home Inspector's Blog


How not to do insulation

I wish there was a way to write this without sounding like my typical rant about the qualities of fiberglass insulation, but alas that would have to be the fault of fiberglass insulation.

I am not sure why, but it seems builders (insulation contractors) like to change from fluffy types of insulation they install in flat areas to batt type insulation in sloped areas.

For example let’s say the master bedroom has sloped ceilings while the rest of the rooms have flat ceilings. These sloped ceiling are often created with scissor trusses that allow for attic space while at the same time create the sloped ceiling—like the one in the following picture with a nice ceiling fan.


When fiberglass batts are used in ceilings it can be very difficult (actually impossible) to install them such that there will be no gaps where air in the attic could find its way around the batts or that air leaking from the interior can find its way into the attic. Modern houses should be sealed such that this cannot happen, but too often sealing is not any more properly done than the installation of the fiberglass batts.


Imagine square edge batts installed on the slope of the ceiling. When they get to the top, unless the ends are somehow cut to a taper, there will be a triangular gap left with little to no insulation. This next picture is looking down between the ends of the batts with the drywall visible below.

Heat loss at insulation gaps

With infrared thermometer one can see how warm the ceiling is in comparison to the attic.

insulation gaps

This cap ran about 15 feet across the bedroom ceiling.

heat loss

This is new construction and it is very important that the thermal barrier be consistent and continuous—especially when the insulation is fiberglass.


Charles Buell, Real Estate Inspections in Seattle

* * * * * * * * * * * * * * * * * * * * * * * * *

Seattle Home Inspector


The Human Rights Campaign   QR code for Charles Buell Inspections Inc


WA State, Home Inspector Advisory Licensing Board

Comment balloon 4 commentsCharles Buell • November 25 2015 05:15AM
How not to do insulation
I wish there was a way to write this without sounding like my typical rant about the qualities of fiberglass insulation, but alas that would have to be the fault of fiberglass insulation. I am not sure why, but it seems builders (insulation… more
Out of sight—can mean out of one’s mind!
The house I want to talk about today, originally had a three car garage. Very early in the life of the home, perhaps dating even to the time of construction, someone decided one of those garage bays would become living space. In this first picture… more
How to flash siding butt joints
A common problem with cement board siding products (and some other types of horizontal lap siding) is that older installation guidelines called for caulking the joint instead of flashing the joint. This has proven problematic over time as caulking… more
There are still a lot of these recalled toilet tanks out there.
If you flush the toilet and it sounds like there is some sort of jet engine in the tank, it may be a compressed air, assisted flush, type tank. These flushing mechanisms work REALLY well but some of them, like the Sloan Flushmate III/503, are… more
Sick of mold or sick from mold?
While you are not likely to get sick from mold, there is a good chance that if you are a real estate agent, or home inspector, or banker, or appraiser, you may very well be sick of hearing about mold. This post will be the first in a series of five… more
Mold on the roof sheathing---and the home is new!
There is some staining/discoloration and/or mold or mold-like fungal growth present on the roof sheathing in the attic. This condition may be consistent with the effects of Night Sky Radiation. Night Sky Radiation is when the roof sheathing… more
How do short inspection contingencies benefit buyers?
I know I may be stepping into quick-sand with this question, but I am serious. I do not pretend to know all the intricacies of how the real estate world works from an agents point of view but I do know what I see as an inspector. All too often I see… more
Are Red Flags Ruining Your Day?
So you have purchased a house, totally remodeled it and it looks beautiful! Time to flip it, go sit on a beach somewhere, and drink margaritas. The listing says something like: “Remodeled down to the studs and looks just like new construction… more
The vented vent
B-vent exhaust vents extend above the roof and provide a way for furnace or water heater combustion by-products to get to the exterior of the building. They often rust at the section above the roof because the vented gases swirl around the pipe… more
Grandfather has left the building
For years it has been common wisdom that older electrical panels were somehow covered by Grandfather. Grandfather is this mysterious guy who never played an electrician or TV, was never a home inspector and was certainly never an electrical engineer… more