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RRM wall expansion joint filler material.

RRM wall expansion joint filler material.

RRM wall expansion joint filler material.

Dear sirs,

Can you please suggest the name of filling material to be used for the expansion joint in Random Rubble Masonry Wall?


RE: RRM wall expansion joint filler material.

That’s a bitch of a wall to put a control or expansion joint in. You have to do the best you can to confine its size/length (along the wall)/shape to a fairly straight line. I would use some sort of closed cell, soft foam, sheet material about .5” (+/-) thick in most of the joint width (wall thickness), to keep mortar out of the joint. I would stop this short of the wall outer surfaces, with enough joint depth for a proper sized backer rod, and then caulk the outside of the joint with a properly proportioned bead of caulking. Talk this over with a good mason, so you and he know what you want and what you are getting. Lots of them will butcher this if you let them. Talk with a good masonry supply house for ideas and specific material names.

RE: RRM wall expansion joint filler material.

I've inspected a lot of stone walls; random rubble masonry doesn't have any expansion joints. With that said, people have different descriptions of RRM. IN NYC RRM is just that, stones piled/laid up; no (or minimal at best) horizontal or vertical continuity of joints between adjacent stones; some surfaces may be cut to get things to fit. Where you are, is ashlar considered RRM? Again, where I am, ashlar has cut bedding surfaces. Ashlar can have any expansion joint. Use caulk that complies with Federal Specification TT-S-230 Sealing Compound, Synthetic-Rubber Base, Single Component, Chemically Curing. The caulk would be applied over premoulded joint filler meeting the requirements of ASTM D1751.

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