[Drews29]

Hi, I'm currently building a free standing a porch that will butt up to a camper and be lightly attached for sealing purposes. It will be enclosed with Jalousie windows and a tin roof and I'll have a propane heater and air conditioner out there. Being that I wanted it so that it can be climate controlled I installed a moisture barrier on top of the joists before installing the pressure treated deck boards. The joists are also pressure treated and are essentially ground level on cement blocks. I'm now wondering if I'm going to have a moisture problem under the deck boards between now and the time I finish the walls and roof and I'm wondering if I need to pull a few boards and drain any rain water and maybe cut drain holes in the moisture barrier, or pull all the boards and remove the moisture barrier and put down a subfloor over the deck boards. Hadn't given the rain issue much though til now. I went with pressure treated deck boards simply for the look and feel as well as durability and the fact I didn't want a fully finished floor. Thanks

 

[Bud9051]

Hi Drew,
I always feel bad trying to help people after they are well under way or have completed their project, it makes it hard to provide the proper advice, but you are off to a bad start.

First we need more details.
Where are you in terms of climate?
Is that propane heater vented to the outside?
Anything on the inside below the tin roof?

Your choice of pressure treated wood means it starts out very wet and once dried you will have 1/2" gaps between the boards. Plus PT requires all special fasteners.

The low clearance below the deck will limit ventilation, but if the plastic holds the moisture issues will stay below, don't cut holes. A solid plywood would have been better but you would still have the ventilation issue.

Turning a camper into permanent living space may require permits, have you inquired?

Bud

 

[Drews29]

Thanks for the feedback. I'm leaning towards removing a few boards so I have access to the vapor barrier and just cut it out of there. I'll put vinyl sheet flooring over the deck boards. This is not a permanent structure, it's in a campground and they don't have any issues with this. I'm just worried about moisture under the floor boards at the moment. The heater I'm going with is a ventless 15k btu propane heater from Harbor Freight. They don't need chimneys. I have one in my garage and it works great. Just kind of annoyed I have to spend and hour or so having to cut out that moisture barrier and will not be able to see the wood deck. I couldn't talk the wife into going with caulk between the boards. That would have looked good and served as a moisture barrier. :biggrin2: Oh well.

 

[Bud9051]

You won't miss the splinters though, from experience on my deck.

I know you will defend it, but unvented is a bad idea. Even when it is running perfectly it still puts off a ton of moisture (30,000 BTUs = 1/6th gallon of water), link below. But, a simple speck of dust and the air fuel can get way out of line resulting in CO, which is very bad. Go to sleep with the heater running and never wake up. We lose a couple per year to CO poisoning every year here in Maine.

Be safe,
Bud
http://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/avoid-unvented-gas-heaters

 

[Drews29]

Thanks for the info. I'll take this into consideration.

 

[Bud9051]

Switching from a non-vented to a vented not only eliminates the potential hazard, but it gets rid of that moisture. A cold tin ceiling would be raining.

Bud

 

[Drews29]

good point