UNDERSIDE VEHICLE PROTECTION

[STEVE POLLARD]

Question, I park my vintage vehicles in a detached garage with a cement floor. I had one friend tell me that I should paint the floor with a epoxy paint to protect it and another friend mention that i should lay down plywood to protect the vehicle from moisture. Just curious what some of the members here have done to protect their vehicle from the moisture issue.

 

Thanks !

[Spinneyhill]

If you have a DPC (damp proof course, or layer of plastic sheeting) under the concrete floor, you have no problem. It will prevent moisture coming up into the concrete.

 

If you do not have a DPC under the concrete, then a moisture barrier is a good idea.

 

I recommend any garage floor be epoxy painted. Concrete continually produces dust. Epoxy paint stops that. It is also easy to clean and to wipe up spills without leaving a stain in the concrete.

 

If you want a moisture barrier, you might be better to put one on first, before the epoxy paint. I remember looking at one made by DuPont; it grows crystals into the concrete pores, preventing moisture transmission. I suppose paint does the same thing when it sticks, but crystals will fill the pores and not come unstuck. I was looking at it as a tanking agent for inside my basement, where moisture was bringing calcite out of the blocks; of course it is better on the outside than the inside!

 

Another idea is to lay a DPC on the concrete and another layer of concrete on top of that, with mesh to control crinkage. You could install underfloor heating in this new concrete!

Edited September 26, 2018 by Spinneyhill (see edit history)

[R Walling]

  I looked this up on google. I know nothing about it except what is listed there.

 

https://allgaragefloors.com/polyurea-best-garage-floor-coating-kits/

 

 AND...

 

 

Edited September 26, 2018 by Roger Walling (see edit history)

[Spinneyhill]

Thanks for updating my knowledge! My experience is 9 years+ old now, since we built this house and moved from the one with a seepy basement.

[Frank DuVal]

BTW, plywood is porous, so it does not stop moisture. It will mold and delaminate if exposed to moisture long enough.  Maybe they meant a 6 mil layer of plastic and then plywood over that to protect the plastic?

[billorn]

You will never 100% stop moisture coming through the floor. I just buy one or two cheap box fans and leave them on low speed in the garage to keep the air moving so it doesnt settle on the cars. I run a dehumidifier in the spring and summer. Keep the air moving and it will be ok. Trying to stop moisture from doing what it does is almost imposisble so you just work with it.

[JACK M]

I park most of my cars on old carpets.

I hadn't considered moisture, just didn't want oil spots on the floor.

[auburnseeker]

I have actually used cardboard on concrete floors and had great luck,.  The moisture stays on the bottom layer and the little corrugations give an air barrier between the layers.  It wasn't' a wet garage but just an average one uninsulated that I kept one of my cars in for over 10 years and it never showed any signs of surface rust on the exhaust or chassis.  I was also sure to never open the door on the quick warm up days,  to prevent stuff from sweating. 

I use box fans in my new garage with the gravel floor for the time being, until i can get my new floor poured,  which will be another year atleast.  Though I don't have any old cars stored in it,  just my equipment and daily driver. 

Edited September 27, 2018 by auburnseeker (see edit history)

[STEVE POLLARD]

Great information, I appreciate it. I'll look into the epoxy paint and the box fans.

 

Steve

[60FlatTop]

In an unheated garage the mass of the contents will drop to very low temperatures. Generally a garage has fairly high outside air infiltration rates around doors and especially at the sill plate around the whole perimeter. As warming, moist outside air enters the  garage dew will condense on all the cold surfaces.

This will be my fourth or fifth season of maintaining the heat in my garage to a minimum of 40 degrees, always above the winter dew points. It has cost about $350 annually in the cold area between Buffalo and Rochester New York. I can tell the difference on the cars as well as the other contents of the garage.  The cars never have that light damp moist coat that happened on days slightly above freezing.My floor is unsealed concrete. It heats up quickly to a working temperature. This is a 26' X 40' X 8' building, not super tight or highly insulated. Usually there are four cars so, on a per car basis, the cost is reasonable. I used a standard natural gas residential furnace. It was a take-out from an AC job in 1988. I have been planning to replace it with a suspended horizontal unit, probably with a 2 ton AC unit, maybe next year.

 

An alternative to heating is ventilating. An exhaust fan and intake dampers set to run when the outside temperatures are above freezing to around 60 degrees will bring the chilled cars to ambient temperature quickly. The equalized temperature will stop condensation. I never tried it, but I have seen it work.

[Rusty_OToole]

It would be a good idea to put down a vapor barrier in the form of builder`s plastic, then cover the plastic with old carpet so it does not get torn up. Keeping a fan going to circulate the air is also a good idea.