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belle18 10-19-2011 06:48 PM

building envelope waterproofing
Hey Everyone!

I am renovating a 100 year old frame house. The old wood siding I have been replacing with osb sheathing until I can afford siding. The old wood was so full or holes, rot, and splits it could not be saved. The windows were major issues. The problem I am having seems to be with caulk. The caulk keeps failing in different places. I am using dap 3.0. which has polyurethane and is paintable. An example is my porch. Water is still getting into the beams where the porch meets the osb.

History of that repair. New cement sloped away from house quikcrete for glass block. says its waterproof. Then a thin caulk strip between house and cement. Leaks. I add more caulk wider say 2" wide. Then I paint it with exterior paint. Lasted a couple of rains now leaking again. Same in other places.

What am I doing wrong? Can send pics if I am being unclear.

Thanks for any thoughts,


kwikfishron 10-19-2011 06:53 PM

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Originally Posted by belle18 (Post 752317)
Can send pics if I am being unclear.

Please do. :)
and welcome to the forum.

woodworkbykirk 10-20-2011 10:35 AM

well theres a few different things that can affect the caulking failing..

a) the caulking doesnt last, washes away in rain,, (typical of "DAP" brand caulking even if it does say exterior.. the only thing i buy dap brand for is actual dap for cauling interior trim, if you want to dap the outside you should be using a polybutyl caulk such as Flextra, flex9000 or duraflex. these are all designed specifically for exterior use and can be painted

the other thing is the substrate bond might be failing, if what you were caulking was dirty or wet the caulking wont stick.

also is the osb you are installing getting covered?, it has to be covered with housewrap to stay weather tight, plus your windows and doors need to be properly flashed for them to stay watertight

belle18 10-21-2011 09:58 PM

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Hey wooworkbykirk, thanks for the advice. I looked on line for what you suggested regarding caulk. I will give it a try. Will it stick to painted wood and painted cement? The paint is flat exterior latex.

the substrate was clean, the new cement and new osb. The porch is now waterproof. I can see it underneath from the basement. It used to leak in cement cracks and at the wall joint. I used cement caulk and painted it and it holds now. The entire porch is now all painted with the exterior paint. My goal is a natural colored cement porch down the road once I do the patio below it but this is just trying to stop the water.

Yes, the osb, it is complex. I am building at a later date up. I want all the new siding to match and it will be oiled cedar. The old siding leaks so bad I have been replacing it slowing with the osb. I have had the back osb painted for going on 2 years now and it has held well. Some new osb I used here and on the sides is failing already. Must be the economy, same brand... I do not want to use house wrap because I am using solid foam insulation between the studs inside and am afraid of mold is no way for evaporation.

flashing, So above the windows and doors right? Is above the only place ( top only )? The new windows and frames are all temporary plexi and osb until I get the new siding but flashing make a lot of sense even temporary.

kwikfishron thanks for the welcome! I am so glad to be here : ) Here are the pics.


kwikfishron 10-22-2011 04:32 AM

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Belle, you’re never going to solve this with caulk or anything else that says “waterproof” on the label.

That wall should be sitting above grade on a concrete or block stem wall supported by a footing.

Until you solve that, any attempts you make to keep the water out will at best be just a Band-Aid.

belle18 10-22-2011 11:14 PM

stem wall
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now I see... of course, makes perfect sense.

The old metal door is sort of on a stem wall and no water. The porch is elevated on cinderblocks ( see pic ) but was attached directly to the original house. There was an addition in the 30's and I think the porch later by the style of cinderblocks. Neither porch wall is correct then. Ugh, guess I will pull out the tarp for a while : )

Would something like the door is on be correct? It is a 3-4" stem on top of the porch. I am replacing the door and other wall exterior siding at some point. They are under an overhang so less water penetration and not a priority.

Thanks kwikfishron!

Belle 18

kwikfishron 10-23-2011 06:14 AM

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First off I don’t understand how a wall you have labeled “original house” is built on top of a porch added in the 70’s. looking at the second picture it appears that the wall is built to the outside of what was the original wall. Why?

Whoever added the porch created the problem. What should happen (short version) is for that area to be re-graded and the porch lowered by about a foot.

If this is one of those “that will never happen” situations there is a way with flashing to keep the water away from the house but your window has to be raised and these flashing details would/should be added on Siding Day.

Which leads me to the questions…why would you remove the siding off the house if you're not able to cover it up again?

How long are you planning to live with painted OSB?

I don’t recommend starting any exterior improvements on a house until you can see it through. If the budget isn’t there to do the whole house then fine, do it a wall or two at a time but don’t start what you can't finish.

woodworkbykirk 10-23-2011 09:11 AM

so your not going to put housewrap over the new osb because you are going to put rigid foam "BETWEEN the studs" or over the exterior of the studs

if your just putting foam betwee the studs and not covering the osb you will continue to have leaks. osb isnt waterproof. it can handle only so much wetting then it begins to swell and flake away. now if your going to put foam on the outside thats fine, but make sure it has a ship lap and orientate it so the lap goes down over the lower peice so to shed water.. plus tape all the vertical joints

belle18 10-23-2011 10:25 AM

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Hey wooworkbykirk,

I think I got it. So even once I put siding I will continue to have leaks unless I put a waterproof membrane between the siding and osb.

thanks !

I had assumed the siding would be waterproof but it does only so much, I see, that is why people now use house wrap. ok. will proceed with a new approach there.

Hey Kwikfishron,

I added a sketch. I have owned this house for 4 years. The porch to the best of my knowledge was added in the 70's up against the exterior of the original house and addition. I took off the plastic siding because it was leaking so bad and I could not repair the problems. One plastic was off I could see some problems and was able to do temporary fixes.

We had a tropical storm ( brooklyn ) and that was it. I was up all night literally running emptying buckets all around the house. That is when I decided to remove the wood siding on this section of wall as well. The osb is sitting where the original wall was but there was wood added on top of the original interior beam because of rot for stability.

Lot of incorrect work on the house I have uncovered aside from the porch issues...

on siding day there will be the real windows installed. Now I have plexiglass. I did not flash that because there is no window frame. I thought it would be ok for a while. The back windows have made it a year but now leak.

basically, I am changing the window sizes, layout etc so it made no sense to spend $ to do repairs to put it back to the original form. I had to stop the water and believe me this is 85% better than in the past. It is much warmer also. I used to have a 5 gallon bucket permanently installed in the bedroom wall because after 10 attempts to repair the old wall still leaked. The entire back of the house is all rebuilt now and my bedroom is dry. The windows just started leaking this year. Partly due to the osb frame on them.

I am gonna flash all the top of the windows, they all have a little frame above them, polyurethane the one piece of osb that seems defective and is leaking ( new piece leaked from day 1 ). I will tarp the new porch wall until I can correct its foundation. Maybe add a coat of paint to the osb so it hopefully will take me till siding day which will come a lot sooner if I can stop chasing water out of the house and earn some $$ : )

Thanks for pointing me in the right direction!

Belle 18

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