gap between house and chimney

[sgcsalsero]

Cleaning my gutters out when I noticed I have a rather -concerning- gap between the house and chimney, the widest part at the top. The chimney is not original to the house (built 1920), added on a min. of 30 years ago. Just looking for any opinions, level of concern, and what, if anything, I should do (btw there is shake siding behind chimney).

--Thank you--

 

[bmwbj]

There should have been "ties" in the connection between the chimney and the house. But more than likely water
got between the two and frost pushed them apart. It is not going to fix itself, it does need attention. Call your favorite builder of mason and have them inspect if for integrity. I'm thinking a rebuild may need to be done IMHO.

 

[jtp10181]

Shouldn't the masonry of the chimney be 2" clearance from and combustibles according to NFPA 211?

 

[EatenByLimestone]

I built mine away from the house. My father's was built the same way. I'd only worry about any birds that make a nest in there. If the siding is between the chimney and house, the chimney probably didn't pull out.

Matt

 

[elmoleaf]

The chimmney is supposed to be self-supporting and the house likewise.

There are a couple possible reasons for the gap.
1. Intentionally built that way.
2. Wood siding has shrunk away overtime from mortar that was put against it.
3. Chimmney going out of plumb over time due to structural problems. Use a plumb bob (or a just get some string and a weight) and drop the line from the top outside corner of the chimmney. If the line hangs out in space away from the face of the masonry, then your chimmney isn't vertical. If the tilt is small, measure the gap and check again in a few months to see if it changes.
If it's far out of plumb, you can probably see that without a line.....in that case, consult a mason.

If no structural action needed, you can fill the gap to keep out insects, moisture etc with backer-rod and sealant or low-expansion foam.

 

[webbie]

Folks are right about there is supposed to be a gap - BUT, this gap was not common practice - and may still not be in many areas without good inspectors or smart contractors and masons. Masons often have a "always did it this way" type of attitude.

My guess is that the chimney foundation is settling and the chimney is pulling away - a relatively common occurrence. In this case, a little bit of it might be a slight bonus in that the chimney becomes closer to code.

Elmo gave some good advice. What I would add would be these possibilities:

1. Have some wrought iron brackets fabbed which fit around the chimney and bolt to structural places of the house - like the top rafter, floor joint band, etc. - two of them would probably be nice. Use either large lags, or better yet - if attic is accessible, maybe through bolt to end rafter. Note, this is from afar - your carpenter may want to tie that rafter into the other rafters with some boards across the bottom to spread the load.

2. We had an installer back in NJ who actually fixed a bunch of these chimneys when they leaned too far. Such a job would be over the heads of most residential carpenters, but with the right heads and planning, it can be done! What he did was to actually prop boards against the chimney and also dig around it's foundation - then slowly used railroad jacks to support the entire chimney foundation and also to push it back against the house (mostly by lifting up on the outside of the chimney foundation - but at the same time, pushing those boards which were against the outside of the chimney).....

Then he would pour a bunch of yards of concrete around it, burying the jacks and all (he bought the jacks cheap at flea markets, etc.)......

Wow, that is like brain surgery. But, you might be able to do a mini-version by using those brackets and then digging around and enlarging the foundation (pouring more crete) - this would not raise the thing, but perhaps stop it from leaning any more.

It would certainly help if you knew an engineer. My buddy (in NJ) actually got permits for these jobs, as they were done to satisfy insurance companies - strangely enough, it turned out that homeowners insurance covered it for some folks! I'm sure the building inspector looked and shook his head, thinking "heck if I could do a job like that"....as I said, not for the timid. Not your typical Home Depot job!

 

[webbie]

FYI, look at the bottom of this page:
https://www.hearth.com/gallery/pics/chimney/source/chimneypotsdavis.html

at the stability washers

and pics like:
https://www.hearth.com/gallery/pics/chimney/source/holy1.html
https://www.hearth.com/gallery/pics/chimney/source/yellowbricknew.html

See how houses are used to make the chimney more stable?

 

[Reggie Dunlap]

If you think the gap is recent or getting bigger I'd investigate furthur to see if the chimney is out of plumb. It may be that the ground under the footing settled after it was built 30 years ago. If it just moved a little and hasn't moved since I wouldn't worry about it.

If it were my house I'd have a structural engineer take a look. I would not tie the chimney back into the house without determining what is going on.

Reggie

 

[sgcsalsero]

Wow, lots of good info, thanks.

Hey Craig, whenever you and Corie get the stove donor thing going again count me in for a few dinero.

 

[JimWalshin845]

Yep... footings on the chimney sunk or cracked. Shouldn't be a real concern. Measure it and caulk it and see if the gap widens over time.