Retrofit foam adhesive masonry veneer ties
Retrofit foam adhesive masonry veneer ties
(OP)
I read an earlier thread in which Ron stated that he has used expanding foam adhesive to tie masonry veneer to its back-up when the original ties had failed. I have never heard of this before and had the same initial reaction as hokie66, but I am interested in learning more. I frequently deal with heritage masonry buildings that require remediation of the ties between inner & outer wythes & we usually use drilled-in helical anchors. Stone walls with failed inner cores are usually grouted, but the possibility of using foam in them offers the added benefit of insulation. I am looking at an 1830s building with this problem right now. Has anyone ever done this?





RE: Retrofit foam adhesive masonry veneer ties
If it is a wall intended to be be a multi-wythe bonded wall instead of a veneer, that is a totally different situation.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Retrofit foam adhesive masonry veneer ties
Ron (Structural) 13 Jul 10 17:55
I have used expanding foam adhesive for similar application of a historical building of about the same era. Works fine, you just have to be careful to control the foam's volumetric expansion so that you don't blow the bricks off the wall.
hokie66 (Structural) 16 Jul 10 22:58
I have used the screened adhesive anchors for brick veneer, and think it should work for stone. I don't like Ron's idea of filling the cavity with foam, but he generally has good reasons for his suggestions.
Ron (Structural) 17 Jul 10 16:10
hokie66...the cavity is not filled. The foam is injected in dollops at about the same spacing as you would normally have wall ties. The locations are offset so as not to impede drainage or air flow.
RE: Retrofit foam adhesive masonry veneer ties
I'm a bit confused by this comment...
The foam does not replace grout or mortar. It adheres the back side of the brick to the face of the substrate, assuming the substrate is something amenable to an adhesive, such as masonry, cast in place concrete, or in older buildings, structural clay tile.
As noted in the other thread, it is placed in dollops of about 6 inches in diameter, a little more perhaps, but not much less. Insertion points are typically through holes drilled in the mortar joints, preferably at an intersection between the vertical and horizontal joints.
Try a small area on the building. Play with the expansion rates and application rates. We did our mock-up testing on brick against concrete, in an effort to keep from pushing the brick out from the wall.
This method is being proposed on an existing building at a local university. The building is less than 10 years old, is 5 stories of brick veneer over masonry and cast-in-place concrete. I will post if I hear on the acceptance of the method.
Good luck.
RE: Retrofit foam adhesive masonry veneer ties
Yes, I understand how you are using it but I am wondering if it could be used in a stone masonry wall that was built with inner and outer faces of dressed stone and a rubble core. This is a common 19th century wall and the core is frequently full of voids after a century or 2 of the poor lime mortar leaching away. We usually grout the core with low-pressure, low-strength grout injected through ports in the mortar joints to consolidate the core and rebond it to the faces. If low-expansion foam were used instead, it could do the same job as well as adding some insulation value, but I have never heard of anyone trying it. What do you think?
RE: Retrofit foam adhesive masonry veneer ties
RE: Retrofit foam adhesive masonry veneer ties
Dik
RE: Retrofit foam adhesive masonry veneer ties
RE: Retrofit foam adhesive masonry veneer ties
I assume the expanding foam adhesive is a urethane product; do you have a particular product that you have used. I've not used method this but have heard of it being used.
I know about the rubble problems; many old timberframed barns have rubble filled walls and have reinforced a few...
Dik
RE: Retrofit foam adhesive masonry veneer ties
Ron
RE: Retrofit foam adhesive masonry veneer ties
RE: Retrofit foam adhesive masonry veneer ties
Ron
RE: Retrofit foam adhesive masonry veneer ties
RE: Retrofit foam adhesive masonry veneer ties
Most likely multiple wythe. Any consideration to using vacuum extraction to remove debris/rubble?
RE: Retrofit foam adhesive masonry veneer ties
RE: Retrofit foam adhesive masonry veneer ties
RE: Retrofit foam adhesive masonry veneer ties
From the small reconstruction area, you can probably determine how best to proceed with the remainder of the rework.
I'm not sure of the thickness of the exterior veneer, but if it is more than 4 or 5 inches, I wouldn't consider the foam to be viable without some supplementary tie backs as well.
RE: Retrofit foam adhesive masonry veneer ties
You may have difficulty with the urethane type of adhesive. It may tend to creep; you have a slight curvature to the wall with an outward compression component. YOu may want to look into stainless steel spiral ties. They may perform better under tension.
The alternative of removing the curvature from the wall is fraught with difficulty. The wall will act as a 'Jack' arch if you try to compress it inwards. Incredible forces will be required.
It may be possible to provide a temporary support for the upper portion and reconstruct the curved part. This is very expensive and great care must be exercised. It is also the most 'correct' way to restore it.
Care must be chosen in repair mortars notwithstanding the manner of repair, and a detailed analysis of existing mortar *must* be undertaken and a new similar mortar batched. There are specialist Architects and Engineers that you may want to consult with and the US Parks Board has specialists in historic restoration.
Dik
RE: Retrofit foam adhesive masonry veneer ties
Have you determined why the wall has bowed outwards?
As the curvature increases, so does the force tending to push it outwards (trivial comment).
Dik
RE: Retrofit foam adhesive masonry veneer ties
I was initially looking at partial rebuilding along with grout and helical ties when I saw your previous thread about foam, which led me off on this path. I have dealt with historic buildings and masonry for a lot of years and never heard of the foam method before so I was curious. Believe me, it won't be used unless I think it will work and be appropriate and then I'd have to convince a few other people.
Dik: I have specified historic mortars for quite a few projects and am pretty familiar with them. This is about the 8th or 9th Canadian national historic site I've worked on. The wall is continuously supported now at the upper belt-course and I have movable shoring that is in shorter lengths and will be placed to allow removing the outer face in 5-6' widths down to grade as required. Once we remove the face we will see better why it has bulged out; the interior face is more or less where it started. The wall is really more like a set of piers: there are interior recesses so the thickness under the windows is only 8" & it is 24" beside the windows.
RE: Retrofit foam adhesive masonry veneer ties
Is the inside of the wall plumb? or, does it exhibit a similar curvature? Interesting that a 24" wall at the corner of a building has a curvature.
Dik
RE: Retrofit foam adhesive masonry veneer ties
Dik
RE: Retrofit foam adhesive masonry veneer ties