Waterproofing "stucco" window sills

Reply

  #1  
Old 04-25-17, 11:00 PM
N
Member
Thread Starter
Join Date: Oct 2003
Location: San Diego
Posts: 687
Received 1 Vote on 1 Post
Waterproofing "stucco" window sills

Just bought a house that was built I think in the 80th. The builder decided to get fancy and used those hard foam forms to build window sills. They pretty much all failed and I am sure causing some water intrusion. I am going to repaint the house possibly using elastomeric paint to keep it waterproof, but what can I use to fix all the window sills? I doubt they are really capable of supporting a layer of stucco on top of them. Maybe a thinset?
Thank you,
 
  #2  
Old 04-26-17, 04:04 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,964
Received 6 Votes on 6 Posts
Not being able to see what you see puts us at a disadvantage. You can add pictures. It is possible that the foam forms can be cut out and normal PVC sill nosing installed, but we can't advise adding stucco to failed stucco.
 
  #3  
Old 04-26-17, 04:55 AM
M
Forum Topic Moderator
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 47,945
Received 384 Votes on 340 Posts
Pics would help! Once you've got the repairs done, caulking any cracks/joints and using an elastomeric paint will waterproof it about as good as you can. Is this a block house or wood framed?
 
  #4  
Old 04-26-17, 08:32 AM
N
Member
Thread Starter
Join Date: Oct 2003
Location: San Diego
Posts: 687
Received 1 Vote on 1 Post
I will take pictures and post them as soon as I can.
The house is wood framed full stucco. It doesn't rain here too often, but when it rains it pours, that was the case this spring.
 
  #5  
Old 04-26-17, 08:38 AM
M
Forum Topic Moderator
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 47,945
Received 384 Votes on 340 Posts
Do you know what type of construction it is? Some stucco houses are stucco over block and sometimes foam added for detail. Others are wood frame with the stucco applied to wire lath.
 
  #6  
Old 04-26-17, 09:36 PM
N
Member
Thread Starter
Join Date: Oct 2003
Location: San Diego
Posts: 687
Received 1 Vote on 1 Post
I think it's the wood frame with stucco applied to wire, most homes are built here that way and foam is added for detail.
Name:  IMG_20170426_131724.jpg
Views: 819
Size:  29.4 KB
Name:  IMG_20170426_131719.jpg
Views: 873
Size:  31.1 KB
Name:  IMG_20170426_131746.jpg
Views: 1358
Size:  34.1 KB
Name:  IMG_20170426_131753.jpg
Views: 637
Size:  31.2 KB
 
  #7  
Old 04-27-17, 04:29 AM
M
Forum Topic Moderator
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 47,945
Received 384 Votes on 340 Posts
I'm a painter, not a stucco guy but I'd think you could just restucco those areas. It's possible painting the area with a bonding agent might be best. We have a pro plaster guy who's a member - hopefully he'll have time to chime in with expert advice for you.
 
  #8  
Old 04-27-17, 08:54 AM
N
Member
Thread Starter
Join Date: Oct 2003
Location: San Diego
Posts: 687
Received 1 Vote on 1 Post
Thank you marksr,

I was thinking of some kind of membrane on top of the sill and then waterproofing it with something like Henry's Tropi-Cool coating, but not sure if it's worth or even possible to attach any membrane to this product.
 
  #9  
Old 04-30-17, 09:42 AM
N
Member
Thread Starter
Join Date: Oct 2003
Location: San Diego
Posts: 687
Received 1 Vote on 1 Post
Btt

Wondering what is the bondign agent and if thinset is out of the question.
 
  #10  
Old 04-30-17, 07:24 PM
T
Member
Join Date: Jul 2003
Location: California
Posts: 1,940
Received 15 Votes on 13 Posts
I do not get along as well on the iPad as a pc but here goes. Where in California are you?
Around here the house has the Windows flashed and then the wire lath is installed and the house is scratched and browned.
I guess I should ask at this point if the houses traditional stucco, three coat work about 7/8" thick. If so then the house is browned, the second stucco coat, then the shapes are installed. If the house is properly flashed and lathed then it is unlikely that you have a serious moisture. Problem. The water that does get behind the shape of any will just drain down the stucco or if it gets behind the mortar of e stucco it will drain down the moisture resistant paper and out the weep screed.
If your house is thin coat stucco over foam it is still flashed and moisture resistant paper is installed behind the foam and the shapes,are added to the foam and Either stuccoed or else added after the brown coat.
So to fix the shapes exterior thinset mortar is a pretty good choice. If there is a stucco supplier in your area they will have the material like was used originally.
No matter what material is used the bond of mortar to the foam is not great. If the foam has been exposed to the elements for a few weeks you should abrade the deteriorated foam down to good white, sound foam. Using a bonding agent before your mortar will help but the proper mortar for the job has adhesive included in the mix.
Talking to the local stucco supplier is a good next step.
 
  #11  
Old 05-01-17, 06:52 PM
N
Member
Thread Starter
Join Date: Oct 2003
Location: San Diego
Posts: 687
Received 1 Vote on 1 Post
Thank you for your reply.
I did check, there is paper behind the scratch coat, at least I hope it's a scratch coat. The whole house is built weird. The drywall applied over some plaster material, bathroom has "open" can lights, travertine is used as kitchen countertop, you get he picture.
I'll probably talk to the stucco supplier tomorrow to see if they have any ideas for me.
 
  #12  
Old 05-07-17, 09:25 PM
A
Member
Join Date: Oct 2008
Location: San Diego
Posts: 69
Received 0 Votes on 0 Posts
The moldings are, or should be, applied over the top of the scratch coat using a thin-set adhesive. The stucco finish coat is then applied over everything (walls and molding) to provide a seamless integrated appearance. The 'failed' stucco finish as pictured on top of the sill should not lead to water intrusion, if installed correctly. The moldings are primarily cosmetic.

If the sill molding is loose or falling away from the wall then it should be removed and a new molding installed using thin-set or other similar adhesive or even exterior grade liquid nails. Finish stucco is reapplied.

If the sill is just flaking, as it appears in the pics, remove all the loose stucco, coat with a concrete bonding product and simply apply stucco patch to match existing finish. Elastomeric paint could be installed over the sill, when completely dry for further water proofing and additional stability.

If you are experiencing water intrusion into the home I would be looking for another cause. With shoddy workmanship who knows what short-cuts the contractor made to save a buck or two.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: