Masonry watersealers

[drooplug]

I just had my chimney cleaned by a local company. The guy said everything was in great shape but recommended sealing the exterior with a watersealing product to prevent the chimney from deteriorating. Are these products worthwhile and necessary?

 

[Planeweird]

simply put....Yes.

 

[jdinspector]

yes, they are. However, you have to be careful about the type of sealer. You MUST use something breathable. That is, it should be waterproof, but vapor permeable. (Think Gore-tex for your masonry) High tech science stuff. Silicone based sealers can do more damage than they prevent, however penetrating siloxane sealers have the waterproof/breathable property. Also, keep in mind these products do not bridge cracks or voids. Therefore, the masonry and the chimney crown must be in good condition.

 

[jdinspector]

I re-read your post. Are they worthwhile? Yes. Are they necessary. No, not if the masonry is in good condition and shedding water properly. Now go back and read my previous post about the type of sealer you should use.

 

[drooplug]

I re-read your post. Are they worthwhile? Yes. Are they necessary. No, not if the masonry is in good condition and shedding water properly. Now go back and read my previous post about the type of sealer you should use.

My chimney is fairly new and in good condition. It was rebuilt within, probably, the last 5 years. How would I be able to tell if the chimney is shedding water properly? I did have efflorescence over the winter.

The chimney company that recommended the sealer uses ChimneySaver which has the properties you spoke of.

 

[jdinspector]

If the chimney is new and in good condition, I wouldn't get too worried about having it sealed. How much does the sweep want for the sealing?

As far as determining whether it is shedding water properly, if you don't see too much dark water staining (depending on the color of the brick) after a rain and there is a good crown with a good overhang, you're probably OK. It's the intricate chimneys that I see that tend to have big problems. I've put an illustration of a good simple chimney top below...

 

[drooplug]

If the chimney is new and in good condition, I wouldn't get too worried about having it sealed. How much does the sweep want for the sealing?

As far as determining whether it is shedding water properly, if you don't see too much dark water staining (depending on the color of the brick) after a rain and there is a good crown with a good overhang, you're probably OK. It's the intricate chimneys that I see that tend to have big problems. I've put an illustration of a good simple chimney top below...

He said about $200 for my chimney. I Don't have the overhang at the top as in the picture. Not sure what it the rest looks like. I'm not sure my ladder will get up that high for me to check it out. I'll try to get some pictures up of my chimney so you have an idea.

 

[dvellone]

It looks like you might have some efflorescence occurring in your chimney. This happens when rain water or condensation cause mineral salts to leach out of the mortar or masonry units. Typically it is a clear indication of moisture getting into the masonry structure from behind or above. The moisture migrates outward leaching the salts. In the case of chimneys I see it most often where there is either no cap or where the cap is failing and allowing water in. In the long shot of your house it looks like there isn't a cap. Maybe the angle is hiding it. Water can also enter from failing flashing. It looks like your chimney is built against a rake edge and I can't see a cricket. Whats the flashing like on that side? Could be some of the problem though it looks like the efflorescence is occurring above the flashing point.

The good news is that efflorescence in and of itself isn't a big problem but instead indicates water entry someplace. " Breathable" sealers will allow a minute amount of moisture through at best and in your case, if efflorescence is in fact going on, will cause greater problems by trapping the larger amount of water that's getting into your chimney. The sealer will lead to spalling and rotting of the joints and brick. I might find a local sweep or mason that can check it out closely and see where the water is getting in. It looks like this chimney has been recently repointed and you don't want to jeopardize that investment.

 

[drooplug]

It looks like you might have some efflorescence occurring in your chimney. This happens when rain water or condensation cause mineral salts to leach out of the mortar or masonry units. Typically it is a clear indication of moisture getting into the masonry structure from behind or above. The moisture migrates outward leaching the salts. In the case of chimneys I see it most often where there is either no cap or where the cap is failing and allowing water in. In the long shot of your house it looks like there isn't a cap. Maybe the angle is hiding it. Water can also enter from failing flashing. It looks like your chimney is built against a rake edge and I can't see a cricket. Whats the flashing like on that side? Could be some of the problem though it looks like the efflorescence is occurring above the flashing point.

The good news is that efflorescence in and of itself isn't a big problem but instead indicates water entry someplace. " Breathable" sealers will allow a minute amount of moisture through at best and in your case, if efflorescence is in fact going on, will cause greater problems by trapping the larger amount of water that's getting into your chimney. The sealer will lead to spalling and rotting of the joints and brick. I might find a local sweep or mason that can check it out closely and see where the water is getting in. It looks like this chimney has been recently repointed and you don't want to jeopardize that investment.

The chimney was rebuilt from the ground up. The flue was clean as a whistle until we lit a fire this past winter.

There is a cap on both flues. Though it wouldn't take much for rain to get in anyway. There is no overhanging crown, though.

Are you saying that because I have efflourescence I shouldn't use the sealer?

 

[summit]

a chimney cap would be a good start, then apply a water sealer every 2 yrs

 

[summit]

to add on that... a cap that covers the entire top.. check out chimcap

 

[dvellone]

It looks like you might have some efflorescence occurring in your chimney. This happens when rain water or condensation cause mineral salts to leach out of the mortar or masonry units. Typically it is a clear indication of moisture getting into the masonry structure from behind or above. The moisture migrates outward leaching the salts. In the case of chimneys I see it most often where there is either no cap or where the cap is failing and allowing water in. In the long shot of your house it looks like there isn't a cap. Maybe the angle is hiding it. Water can also enter from failing flashing. It looks like your chimney is built against a rake edge and I can't see a cricket. Whats the flashing like on that side? Could be some of the problem though it looks like the efflorescence is occurring above the flashing point.

The good news is that efflorescence in and of itself isn't a big problem but instead indicates water entry someplace. " Breathable" sealers will allow a minute amount of moisture through at best and in your case, if efflorescence is in fact going on, will cause greater problems by trapping the larger amount of water that's getting into your chimney. The sealer will lead to spalling and rotting of the joints and brick. I might find a local sweep or mason that can check it out closely and see where the water is getting in. It looks like this chimney has been recently repointed and you don't want to jeopardize that investment.

The chimney was rebuilt from the ground up. The flue was clean as a whistle until we lit a fire this past winter.

There is a cap on both flues. Though it wouldn't take much for rain to get in anyway. There is no overhanging crown, though.

Are you saying that because I have efflourescence I shouldn't use the sealer?

Yes. The efflorescence is indicative of a larger amount of water entering the chimney than the sealers will allow to migrate out. The misconception about sealers is that they somehow have an ability to prevent water from entering the masonry units, but then allow water to escape. They don't work that way. They "seal" both ways so that if you have water entering from above or behind the structure they will inhibit it's escape enough to cause real problems. The "breathability" is somewhat like putting tung oil on your woodwork instead of paint. The tung oil penetrates to protect but doesn't "seal" the wood like a film of oil-based paint would.
I would first get a cap on the chimney with a minimum 2" projection. Then I'd make certain that water isn't entering at the flashing. Next clean the efflorescence off the chimney with a stiff synthetic brush. If this doesn't remove the efflorescence, or if its real heavy you can remove it with 1 part muriatic acid to 12 parts water. Add the acid to the water. Wet the chimney prior to washing and rinse it well after. Don't forget the saftey goggles and gloves - the acid as well as it's fumes are very corrosive. Now leave it as it is through the summer and fall checking to see if the efflorescence reappears. If it doesn't you can then apply your sealer.

 

[jdinspector]

to add on that... a cap that covers the entire top.. check out chimcap

I agree with this too. Initially, I envisioned a concrete crown on the top of the chimney, similar to what I showed in the illustration I posted. (Incidentally, I use the term crown, when cap is also used. I think that's local vernacular. In either case, it's a cap). Just make sure that whatever you used, it covers the entire chimney top.

I looked at chimcap.com. Those will work fine. However, you have a nice looking chimney. A more intricate copper or other type of metal cap would look great and would also do what you want. Try the local sheet metal shops. Many around me will custom make them for you. I don't have any idea of cost.

 

[jdinspector]

It looks like you might have some efflorescence occurring in your chimney. This happens when rain water or condensation cause mineral salts to leach out of the mortar or masonry units. Typically it is a clear indication of moisture getting into the masonry structure from behind or above. The moisture migrates outward leaching the salts. In the case of chimneys I see it most often where there is either no cap or where the cap is failing and allowing water in. In the long shot of your house it looks like there isn't a cap. Maybe the angle is hiding it. Water can also enter from failing flashing. It looks like your chimney is built against a rake edge and I can't see a cricket. Whats the flashing like on that side? Could be some of the problem though it looks like the efflorescence is occurring above the flashing point.

The good news is that efflorescence in and of itself isn't a big problem but instead indicates water entry someplace. " Breathable" sealers will allow a minute amount of moisture through at best and in your case, if efflorescence is in fact going on, will cause greater problems by trapping the larger amount of water that's getting into your chimney. The sealer will lead to spalling and rotting of the joints and brick. I might find a local sweep or mason that can check it out closely and see where the water is getting in. It looks like this chimney has been recently repointed and you don't want to jeopardize that investment.

The chimney was rebuilt from the ground up. The flue was clean as a whistle until we lit a fire this past winter.

There is a cap on both flues. Though it wouldn't take much for rain to get in anyway. There is no overhanging crown, though.

Are you saying that because I have efflourescence I shouldn't use the sealer?

Yes. The efflorescence is indicative of a larger amount of water entering the chimney than the sealers will allow to migrate out. The misconception about sealers is that they somehow have an ability to prevent water from entering the masonry units, but then allow water to escape. They don't work that way. They "seal" both ways so that if you have water entering from above or behind the structure they will inhibit it's escape enough to cause real problems. The "breathability" is somewhat like putting tung oil on your woodwork instead of paint. The tung oil penetrates to protect but doesn't "seal" the wood like a film of oil-based paint would.
I would first get a cap on the chimney with a minimum 2" projection. Then I'd make certain that water isn't entering at the flashing. Next clean the efflorescence off the chimney with a stiff synthetic brush. If this doesn't remove the efflorescence, or if its real heavy you can remove it with 1 part muriatic acid to 12 parts water. Add the acid to the water. Wet the chimney prior to washing and rinse it well after. Don't forget the saftey goggles and gloves - the acid as well as it's fumes are very corrosive. Now leave it as it is through the summer and fall checking to see if the efflorescence reappears. If it doesn't you can then apply your sealer.

I agree with this post too. Too often sealers are used that have no net effect, or worse, they add to the problem. I like the approach above. Take it step by step and I’ll bet it will all work out fine. If you find a flashing leak, I think you have to talk to the guy who rebuilt the chimney. Surely he would like to know about the deficient work (yeah right!)

Really, you have a pretty intricate chimney. It's tough to have good mortar joints in stone that will keep water out. I was assuming that you had a brick chimney. Also, since your chimney is wider at the bottom, some water entry at the lower portions is going to be inevitable. Trying to keep water off of it starting at the top is going to be your best bet.

It's a beautiful chimney!

 

[drooplug]

to add on that... a cap that covers the entire top.. check out chimcap

I agree with this too. Initially, I envisioned a concrete crown on the top of the chimney, similar to what I showed in the illustration I posted. (Incidentally, I use the term crown, when cap is also used. I think that's local vernacular. In either case, it's a cap). Just make sure that whatever you used, it covers the entire chimney top.

I looked at chimcap.com. Those will work fine. However, you have a nice looking chimney. A more intricate copper or other type of metal cap would look great and would also do what you want. Try the local sheet metal shops. Many around me will custom make them for you. I don't have any idea of cost.

I have caps up there already.

 

[summit]

to add on that... a cap that covers the entire top.. check out chimcap

I agree with this too. Initially, I envisioned a concrete crown on the top of the chimney, similar to what I showed in the illustration I posted. (Incidentally, I use the term crown, when cap is also used. I think that's local vernacular. In either case, it's a cap). Just make sure that whatever you used, it covers the entire chimney top.

I looked at chimcap.com. Those will work fine. However, you have a nice looking chimney. A more intricate copper or other type of metal cap would look great and would also do what you want. Try the local sheet metal shops. Many around me will custom make them for you. I don't have any idea of cost.

I have caps up there already.

you have caps that cover the individual flues, but do not encompass the whole top... a lot of water sits up there...

 

[Retreadsme]

My chimney was built incorrectly by having the top row of brick inset instead of overhanging the row below allowing water to flow down the sides of the chimney. The mortar cap over time cracked which added to the problem of water infiltration, efflorescence, and brick spalling. All the advise given above is right on target IMO. The cap they are referring to is called a "Chase Cover". I am having one made with a large cap attached to the cover (top removable for flue access). This is the route I am taking to hopefully stop future problems similar to what you described.