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Exterior concrete window sill repair


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Concrete block home in west-central Florida.

A few light taps with a hammer and now one of my sills is near flush to exterior wall. My options are this: http://www.leucht.com/blog/2007/02/repl ... rior-wall/ or grind/cut it flush with exterior wall and repair with quick set adhesive concrete. Leave it flush with no extension.

Unlike the repair in the link I would add re-bar to the extension if, I go that route. Is the extension for window sills purely cosmetic or there for drainage as well?

Should I trowel-cement/seal-primer/paint the portion of the wall underneath the sill? My home is coated with a "Sparkle Crete" which was very common on older homes in my area decades ago.

All suggestions welcomed

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The rebar is rusted but still solid. I have another sill located in the back of the house that was crushed by a fallen oak tree. The guy that fixed it made it flush against the exterior wall and it's been fine for the past 11 years. That's why I asked if an extended sill is just cosmetic, especially with a CB home that has a type (sparkle-crete) of stucco.

The sill in the pics is the only one on that side of the house and may not look out of place much if repaired flush. Seems like most newer homes don't use extended sills. I am afraid I am talking myself into the easy way instead of the right way and need input of the brain-trust here to get me motivated to do it right the first time around.

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If you repair it with an extension.....it won't work unless you cut a drip groove into the bottom edge to keep water from simply running back into the wall.

What if you repaired it flush and put a simple sheet metal drip cap on it?

I like the idea of it draining, but given the look of the place, I'm not so certain it's really necessary.

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I agree that a window sill on a mass wall construction is cosmetic. It isn't a multistory CB construction in direct contact with wood joists so if you don't mind how it looks then any repair that sheds water and won't be threatened by the expanding rust on the rebar should be fine.

That's just my guess. I've never encountered this type of construction on the job, just on TIJ. Others with hands-on experience will chime in, support me, rebuke me, whatever.

Marc

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I don't recall the sill that was repaired flush 11 years ago having any material other than concrete. He may have used waterproof concrete. Wouldn't a metal cap (besides stainless) rust?

Also, on the first image I posted it shows a more porous, grey concrete underneath the harder, whiter (portland) concrete where the rebar was embedded. Is it best that I cut all of that softer grey concrete out and replace it, or repair over it?

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Kynar coated galvanized won't rust, and you could get it in white.

After a third look, I'm not so sure it matters.

I might repair it with vinyl cement, quikrete or similar, and do it flush. Finish it by feathering in new stucco.

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Unfortunately, I have jalousie windows on two bathrooms in addition to the garage I posted. I won't be replacing any of them as the house is currently for sale.

I ground it flush with the wall and used this http://www.homedepot.com/p/SAKRETE-10-l ... /100275522 . I plan to use the following steps to cover the new concrete: masonry sealer> white latex primer> white latex topcoat> masonry sealer. Does that sound right? How long should I wait to paint after applying the first masonry sealer?

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If you are only trying to put a band-aid on the sill, then I don't see a problem with your choices, and I don't think "extension or no extension" makes a difference.

Looking closely at your photos, and at the link you provided; I don't think your fix will fix anything other than cosmetics. You don't have a broken sill problem, you have a broken sill symptom. The problem is water intrusion.

What I recommend is that you take it a step further... which may involve a little more work and a few more bucks; and correct what caused it in the first place... and will most probably reoccur.

If you look at the sills in the "how to" link, you will see they are pitched (minimally) away from the building promoting drainage.

Your sills appear very flat and even negatively pitched towards the building. Water that collects there is going to continue to cause damage.

Especially since you indicate a limited number of windows, I would remove the entire broken existing sill, seal/flash the area and then form and pour a sill using high performance grout. It is similar to the material you are buying in the bucket, but in larger bags and about 1/3 the price. If you feel generous, you could stick a couple of pieces of coated rebar in the pour.

I would suggest as much pitch away from the building as possible, and maintain equal clearance to the bottom of the window.

You will be proud of your work and if you are selling your building; it will be 1 less detraction.

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Your sills appear very flat and even negatively pitched towards the building. Water that collects there is going to continue to cause damage.

Steven you have a keen eye and I agree with your assessment. While I don't feel it needs an extension based on the sill that was repaired flush 12 years ago with a good positive drainage and still looks like new, I do think improper drainage was the problem during the home's initial construction and I need to grind down a steeper (positive) slope much like the repair at the back of my home. Fortunately, there is over an inch thick of what appears to be hard, white Portland cement that can be ground into to create the slope.

I will look into the high performance grout you mentioned, do you have a brand or name? So far I am out $7 for the top & bond that I applied already, so not much pocket damage done. The 4-1/2 diamond grinder wheel ($10) worked very well so far during the initial grinding. I will post pics when I get it sorted out. Thanks for all the replies so far.

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I will look into the high performance grout you mentioned, do you have a brand or name?

There are a number of companies that manufacture high performance grout. Dayton and Sika come to mind. You probably will be better off going to your local masonry building supply to locate the product.

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I ground down the sill this morning and it has much better drainage, but will be even better when finished. From what I can see there was a drainage issue on that sill since the home was built. It had a peak that was about a half inch or less in front of the aluminum window frame that would cause water to pond between the peak and the window frame. From the peak to the outer end (yard side) of the sill it had positive drainage, so it may have fooled the builder and inspector as water doesn't leak through the window frame towards inside the garage.

I called this local company http://www.constructionchemicalcorp.com/products.html and the gentleman I spoke to said to expose the rebar a bit more and then epoxy over that, then use a polymer concrete that can be formed to increase the positive drainage slop even further.

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Update: The owner of the supply company I went to sold me a bag of Increte's Spray Deck (white) grout and said I could use Ospho to cure the rebar to black instead of epoxy. I was able to increase the drainage slope and the product seems to very well. Should I wait 30 days to clear masonry seal the new repair?

Steven, I will adding add an extension for aesthetic and drainage. I will use the DIY link I posted, but add in a bar or two of coated rebar. If it turns out well i will most like add one to the sill in the back of my home.

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Update: The owner of the supply company I went to sold me a bag of Increte's Spray Deck (white) grout and said I could use Ospho to cure the rebar to black instead of epoxy. I was able to increase the drainage slope and the product seems to very well. Should I wait 30 days to clear masonry seal the new repair?

Steven, I will adding add an extension for aesthetic and drainage. I will use the DIY link I posted, but add in a bar or two of coated rebar. If it turns out well i will most like add one to the sill in the back of my home.

I would contact the manufacturer (not the supply house) and ask them if the product is suitable and any other application questions you may have.

As far as the prep to the rebar, why would you not simply purchase the epoxy coated rebar and save the entire step of curing the rebar? It sounds to me like the supply house does not have what you want and is selling you what they have.

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The owner of the supply company told me epoxy and grout on the phone the day before and when I talked with him the next day in person I mentioned that I coated a couple times with Ospho and he said that would be good enough. He was a bit odd and may have been working around industrial chemicals too long. I mentioned the epoxy a few times and said I wouldn't need it.

I called Increte and they said the product should work fine for that repair and it will cure in 24 hours. I let it cure three days and put a couple coats of clear (non-yellowing) water based sealer on it today. It came out well (I hope). Could it be an issue during an appraisal because it doesn't have an extension?

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Because I am here and you are there, I cannot comfortably confirm nor deny your repair, but...

Your repair looks just like what it is; a repair.

No matter how nicely you paint it, it will always stick out like a sore thumb, and will be questioned by whomever looks at it.

The reason for the form (in the "how to" info you posted) is to give you a straight edge. Yours is a curvy as my girlfriend in a bathing suit. The problem is that she is supposed to be, and your window sill is not.

The best repair is one that you cannot notice.

I would have tried to blend in the joint (perhaps with a sponge or brush), and after the concrete dries I would use a paint roller to match and blend in the finish.

I would have also taped off the window frame to keep it clean. Now you should carefully clean it.

I don't mean to be critical, and as I stated; it may function well. It is just ugly and obtrusive.

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OK, I'll go redneck.....

If this was architecture (which I devoutly believe is Art), I'd be puking.

Since it's a concrete block house in central Florida, I don't think it's architecture. It's a concrete block house.

If I was inspecting the joint, I'd probably tell folks it's a cheap repair, but it'll probably work for at least a decade and then they can fix it again themselves.

Yes, the rebar will continue to corrode, and eventually make repair necessary again. If it was a multi-story structure where some rusting rebar could cause a life safety hazard or some similarly serious issue, I'd say do it all over again.

But, it's not. It's a single story concrete block house fer chrissakes. We're not talking bleeding on the brightwork here.....

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I don't mean to be critical, and as I stated; it may function well. It is just ugly and obtrusive.

Steven I can handle constructive (no pun intended) criticism well and agree that it could look better than it does. I am the first to admit that I don't like such household projects anymore and look forward to selling my home (if that day comes) and moving into a condo or villa. The conundrum lies in the fact that things have needed to get fixed in this old house and I can only afford to hire a professional for upgrades (not repairs) that I can't do myself.

I tried a brush, a roller, my hand and a flat blade with the grout to emulate the existing exterior coating, but couldn't match the pattern well. IMO the sparkle-crete under the window sill that came off when the sill fell is what makes it look bad. If I matched the old texture for that part only the sill wouldn't even stand out. My wife and I intend to put a few plants along that wall so eventually the sill may not be seen.

I attached a couple pics after one coat of paint.

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