Question:

We want to apply one of your membrane sealers on a warehouse floor. The problem is that moisture is visible upon the surface of the concrete in early morning. The floor is six months old and we think the moisture is condensation and not moisture vapor from within the slab... what can we do to tell the difference?

Answer:

My experience from other, similar circumstances leads me to tell you to use a thin piece of sheet metal and place it on the dry floor surface. The piece of sheet metal should be large (about 20 square feet in size). Tape the sheet metal down with some duck tape in order to seal the entire perimeter edge. Allow it to lay in place at least overnight. Examine the top, exposed surface of the sheet metal the next morning for the presence of moisture. If water is present because of atmospheric condensation, the water will be present upon the top surface of the sheet metal and when you lift the metal sheet, the surface will be dry. There may be a minor amount of moisture under the sheet. This would be from the normal vapor transmission. If, however, the underside of the metal sheet is highly condensed, the problem is probably due to excessive moisture rising through the slab. This may or may not be a problem depending on the origin of the moisture.

L&M LUMISEAL WB is an effective, user-friendly membrane that can even be placed over concrete releasing a moderate amount of moisture vapor. LUMISEAL WB is a low-odor, non-yellowing, low-gloss sealer. It has excellent tire marking resistance. If you're not quite sure of your particular application, or the right L&M product to use to solve your problem... just give us a call. We always appreciate questions from the industry... and yours was one that is frequently asked.