Fireplace/Log home questions

[badger1]

 

 

Wondering if anyone can give me some pointers. I've asked and looked at several examples and cant tell a solid way to go about sealing/protecting the gap/seam where the fireplace enters the dwelling. 

Many times the fireplace is constructed independently before the logs or dovetailed timbers are erected. Other times I have seen the log or timber shell erected with a square opening left available or cut into the structure for the masonry pad/block and chimney to be built "into" the wall. 

My question is regarding the seam or gap between the edge of the fireplace and the log or timber wall. What is the best method of sealing this and protecting it. I have seen some pretty crude ways to do so, but many look to me to be questionable with regard to moisture not being directed away from the logs etc. Is there flashing or sealers? 

Has anyone here built as I described above? Either cut the square hole out of the structure for a fireplace, then built the masonry fireplace in place and if so how did you seal and protect the gap between your structure and the outside while protecting logs from splash etc/moisture. I know idea;;y your eves would go out around the chimney and provide enough of an overhang to protect the rest of the wall below but many times I dont see this. 

This becomes further complicated when one is building a stone fireplace vs brick as the angles are no irregular around the rocks etc. 

Just something I have been wondering about for a while and have not found good answers in books, I've also asked a couple guys I know that have built cabins and they didnt seem to have a solid answer either. The real world examples I have seen, as I said above, I dont think I would be confident in if it where mine. 

Thanks for any feedback/pictures. 

 

[Don P]

The true answer is don't do it. A masonry chunk like that penetrating the wall is thermally not much different than an open window of that size. Extend the building enough to bring the fireplace and chimney inside the wall and then penetrate the roof with the smaller chimney. The warm mass is now inside which helps with heat loss/ thermal flywheel and also makes it draw better and creosote less. The flashing detail on the roof is a flash from the roof deck turned up around the chimney and a counterflash from the chimney turned down around and over the flashing, a slip joint. Doing it this way avoids a splashback problem from an exterior chimney onto the exterior wall as well. In log and conventional construction it is very common to have serious problems with moisture especially around the shoulder area both in the wall and in the chimney. Is there any way you can make this work with your design?

Review the fireplace/ chimney section of the codebook for their clearances to combustibles, details etc, I think that is chapter 10, that affects insurance as well as safety.
Edit, here it is in my VA code;
https://codes.iccsafe.org/public/document/VRC2012/chapter-10-chimneys-and-fireplaces
I held a WI ticket for awhile, they are ummm, unique. double check your codebook on anything you see coming from another state, usually follows model code but not always.

[badger1]

Thanks for the reply Don, I agree I would prefer an interior fireplace personally and will likely incorporate that into my design, This is more of a general question, as I said, I have seen various methods and none look sufficient for protection. Today fireplaces seem to serve more of an aesthetic purpose over function so I dont think the owners are necessarily concerned with optimum efficiency, I would be. 

I also think many who have places built dont realize the importance of protecting wood from moisture. I have seen several structures built (some by professionals) that look satisfactory at construction but then 5-10 yrs later have serious moisture damage. Many dont realize the power of water to find even the smallest cracks etc and work its way in! I also see several structures that dont pay attention to splash from from ground to bottom course, they dont hold the bottom plate up enough from the ground, often times even under a foot. Log construction manual recommends at least 18" I believe but I have talked to several individuals who have built, including my log instructor and I would say, the higher the better, even 24" inches to ensure longevity. 

Seems a waste to spend all the time and money to build a structure that should last multiple lifetimes, only to have serious issues in a decade because due diligence was not done with regard to moisture issues.