I am looking for ideas for a log home retrofit. 20 years old, cathedral ceiling, full basement and double pane glass. Conditioned space 1500 sq'. Blower-door reveals 5500 cfm50, smoke shows lots of air flow around windows, door and corners. This is what I expected though I have liitle experience with log homes. Suggestions?

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Hi Bruce,

The wife and I would like a log home/camp, but as you are learning, they just don't measure up to an energy auditor's dream.  We will shift to stick built and use the simulated log siding. 

Now, I'm still a novice on log homes, but one of the problems I did not like was the way they had to be built to compensate for shrinkage/expansion.  Large gaps were necessary over doors and windows and that may be part of what you are seeing.  I suspect there is a foam product recommended for those cavities, so I would search the log home web sites or talk to the mfg.


On the inside, if they wish to retain the log look, sealing or creating a double wall are options.  Given the complexity I doubt a double wall would be acceptable.

With 20 years on the roof, there might be some justification for adding another layer of rigid up there along with new shingles. Not easy, but could take those ceilings out of the equation.

What is their budget and determination to make improvements?



They are a frugal Swiss National couple in their 70's so each element will likely be discussed at length. Window and door caulking will be first as the trim is simple to remove and replace. The home has probably finished shrinking though it still moves seasonally as most homes do. I wonder if a product like Thompson's Water Seal would have any positive infiltration effect on the exterior. They like the aged wood and are not interested in any "shiny finishes" that many of the log home companies recommend. SIP panel roof replacement is being considered. Currently there is 6" of glass batt between ceiling and roof. There are soffit and ridge vents which to my way of thinking allow free air flow through the roof insulation, not a great idea. 

Hi again,

You are correct, fiberglass along the vent channel is a major source of heat loss and an area where you can extrapolate some good numbers.  With cathedral ceilings the area increases and thus the heat loss.  6" of fg, derated for cold and air flow almost disappears.  If you caught a surface temp on that ceiling, combined with the inside and outside temps, you can estimate the functioning r-value of that assembly.  Covering it with sips would cover those rafters and greatly increase the insulation benefits.  That's one.

Thompson's, I don't think would change much, other than the moisture penetrating the wood, which might have some effect, plus and minus.

A good IR inspection with positive and negative air pressures will spot a lot more than the smoke test.  Plan on taking some time as the thermal mass will react slowly.  Kick over to the IR forum and I'm sure the will have some good advice.  The advantage here is you will target problem areas and be able to confirm they have been improved.

Is this home on a slab or foundation of some sort?  If slab, perimeter insulation against the slab below the logs plus 3 or 4 feet buried out around the entire building will make a difference and do so without changing the nature of the building.  If crawl or full foundation, they can also be addressed with out affecting the log look.

You didn't mention the climate, although I assume it's not quite Switzerland :).


Pondering, in addition, what we would call the top plate, the top of the walls and their connection to the rafters, and related soffit area would be another place to look carefully.  Rarely is a sloped ceiling well sealed to that top plate area and it is always exposed to the cold soffit (under the eaves) area.




This sounds exactly like the log home we weatherized last year. The main problems were in the interfaces of the T&G ceiling and between the door and window frames and their bucks. Clear silicone and latex based chinking from Perma-Chink helped immensely.

Cathedral ceilings should be unvented and air sealed on all sides, then the ridgid foam would help, but if your warm air is exiting through the ceiling, insulation gets you nowhere.

Stay away from the shiny finishes as the poly-urethane tends to blister and stick to oil-based finishes like Penofin. These nourishing finishes can be re-coated without stripping and provide 90% UV protection.

I did a log home several years ago. The main leakage areas were wall, wall corners , cracks between stone chimney and T & G ceiling, and the basement rims along with bypasses to a tuck under garage.Using log home caulk, which has great elastic properties we caulked every horizontal seam along with the corners and chimney connection. The color match was perfect and was not visible after completion. did the same on the T & G ceiling as there was no access from the attic side closed cavitie. Rims and garage connection were dealt wth by standard caulk and foam with 2" foam board insulation.

Log home caulk is the way to go.You need a steady hand on the caulk gun. Tried a power caulk gun and it did not do as well as by

 hand because of the various sizes of the gaps and cracks. Cut your tip as small as possible to prevent too much caulk from getting on the logs. It's easier to add more than to clean up excess. I did use a foam gun on larger cracks to fill in as a backer for the caulk.

I don't remember the exact leakage tart/stop, but I got approx. 1800 cfm reduction.

It might seem to be an overwhelming job with all these joints, but like everything else sometimes the hardest part of any job is getting started.

Bruce-----------After thinking of my reply, I may have jumped to conclusions. I was assuming the log home was a kit that may have T & G joints or groove and spline. What are the characteristics

 of the construction? If it is hand built home with actual chinking the approach will most likely be different from a manufactured home with tighter joints.



This is an older (20?) manufactured log home with matching, machined groves on the mating surfaces.

Bruce----------OK my first post  stands as it is similiar to what you are facing. It's great to recommend building out the interior walls and sealing and insulating them. That is usually not going to fly as folks love log homes because of the LOGS not drywall covering them up.

As to my first post the larger cracks and checks were first filled with gun foam using PUR foam which you can get in black. It blends  into the cracks and a good gun gives excellent controll on bead size.

AS to the log home caulk it comes in any color to blend into the exising finish and also you can get it textured to match any grain-ess that the logs have. Tedious work but it works. Watch the chimney stone, log joints as they move the most from season to season.

The ceiling T & G can be caulked in the same manner. If you don't have access from the attic side just get scaffolding and get started. A good caulk job will not be noticiable and it will stop the air leakage.



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