Sealing Concrete Garage Floor
JennL
| Posted in Expert Exchange Q&A on
Building a new home in CT zone 5. We’d like to protect the garage floor from road salt, oil, and other stains. I’ve read that drying time is about a month per inch of concrete. The slab will be 4″ thick and we plan to use AFM Safecoat Mexeseal. Should we avoid parking in the garage for 4 months then seal it?
We plan install a trench drain to manage moisture from rain and snow and run a dehumidifier in the space. Garage walls and ceiling will be insulated. I am very sensitive to mold and don’t want to do anything to promote it. How will the sealant affect condensation on the slab? Thank you.
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Replies
JennL,
There are sealers designed to be applied while the concrete is still drying. The one I've used is Cure and Seal.
Thank you. I chose the AFM Safecoat because I need one with zero VOCs.
Unfortunately that rules out the products you can apply immediately. However, I have never waited more than a month to apply a sealer, and never experienced problems. The generic advice is to wait 28 days.
You can also perform a Calcium Chloride test. They're cheap and you can do it yourself if you have access to a scale sensitive down to tenths of a gram. Running a dehumidifier in the garage will also help to dry out the concrete moisture faster. You don't need the concrete to be bone dry - it needs some moisture to continue curing for a year or more, though 90% is done after a week and 99% after a month for most concrete.
Why the trench drain? Garage slabs should be pitched to drain out the door and that's enough for most. You don't want flammable liquids to sit and potentially build up in a clogged drain.
The sealant won't have any effect on condensation on the slab. Condensation is purely related to the surface temperature of the slab and the moisture content of the air in contact with it. Limiting condensation requires insulating the underside of the slab to keep it closer to garage room temperature and dehumidifying the garage air as necessary.
Thank you for your response.
Ice and snow melting off the cars accumulated in puddles at low points in the garage we previously owned. The floor was not level, due in part to erosion of the concrete from salt coming off the cars. I thought the trench drain might help collect some of the water.
Maybe a better approach is to make sure the floor is level and sloped toward the doors. Sealing the concrete should help protect against erosion from the salt. I contacted the manufacturer of AFM Safecoat and discovered that they do not make a product suitable for garage floors in which vehicles are stored. I can ventilate well during the sealing process, but I'd like to use an environmentally friendly low VOC product. Any suggestions?
The garage will be insulated and dehumidified. It will not be used as a work area in the winter, but would it be helpful in terms of mold prevention to insulate under the slab and use some electric heat in the winter? What would be the target temperature? I've been getting conflicting advice on this.
Thank you