Cracks in concrete roof slab
Cracks in concrete roof slab
(OP)
I was asked by owner of a newly constructed building to inspect cracks in the top of a concrete roof. The building was constructed in April this year. The cracks were noticed because after heavy rainfall water would leak through the slab and into the building. The crack widths are about 3mm thick but there are quite a number of them on the roof slab, however none appearing on the soffit. The concrete supplier is blaming the contractor for inadequte curing, whilst the contractor is suggesting the concrete mix was not correct.
Question:
Can anyone recommend any products that will seal the cracks or any solutions to this cracking problem. After sealing i would also advise that the slab be rendered with slope to facilitate faster runoff
Thanks for any input
SNaTCH
Question:
Can anyone recommend any products that will seal the cracks or any solutions to this cracking problem. After sealing i would also advise that the slab be rendered with slope to facilitate faster runoff
Thanks for any input
SNaTCH





RE: Cracks in concrete roof slab
RE: Cracks in concrete roof slab
They have injection epoxies to structurally repair the cracks. They have thin set mortars to resurface your roof slab. They have surface coatings to waterproof the slab. And they make a range a carbon fiber composites to strengthen your damaged slab, if necesary.
Their website is www.sika.com, and they are available pretty much world wide.
I have been using Sika products for about 6 years now, and have no complaints.
I agree with dik, you should figure out why the slab cracked first though. That will dictate what type of repair is necessary.
RE: Cracks in concrete roof slab
Simply filling a few cracks won't make it waterproof - eventually more water will penetrate.
RE: Cracks in concrete roof slab
You need to check the cause of this cracks. If it was cause by evaporation of the water or retraction. Others causes should be checked like stiffness, load and the structural slab detaling.
Even well adensed and correct aditived concrete can“t be "water proof". So roof slabs should be protected from rain and high insolation that causes excessive movimentations and craks.
Matrix
RE: Cracks in concrete roof slab
A building has structure, and there 3 mm wide cracks are nontolerable. Then, a roof needs be made damp-proof and both things are requirements of sound construction. And if "caulking" the thing is to be the solution, Sika is a great election.
RE: Cracks in concrete roof slab
Exposed concrete may be the desired surface, say if there are high traffic loads on the roof. Maybe from rolling equipment. If that would be the case, then a typical roofing sheet membrane might not be acceptable. However, I think leaving bare concrete was a mistake on the designer's part if the concrete was intended to provide the waterproofing layer. Definitely, the original reason for leaving exposed concrete should be considered when selecting the repair method.