The Manufactured Housing Forums

I just went under my home again yesterday and found more rust along the beams, outriggers, and other "straps" or frames ... Just about all is turning red and also making concrete red along same underneath. Last fall I added more vents thinking that I didn't have enough, but it is getting worse. Should I get my house rustproofed (sorry - not joking)? Its only 1 yr old. I even thought I saw frozen condensation on the beam but am not sure. If the house is warm but underneath is cold, isn't condensation normal, esp running the ac in the summer?

condensation is normal, you may have to many vents letting the cold air get to the underside of the home where the warmth is..you have to create a medium temperature air pocket between the cold and warm to reduce condensation .(much like a double pane window)..are you on a slab or just footings? a 6 mil. plstic vapor barrier under the home will help with some of the condensation if you only have footings....also when a chassis is built in the plant they are sprayed with undercoating much like a car ..you can get this in spray or gallons at your local auto parts or an auto paint dealer and then just repaint/respray the chassis if you'd like..

Thanks. I have a concrete slab. I had 6 - 1 sq ft vents. I added 4 more 1.5 sq ft when I added the Everrock skirting. I'm confused about the venting, because I don't think I have enough. Yet in IL it can sometimes be damp, and so will the underside if it is fully exposed. I don't think it can truly be "dry" under there. I have no other issues other than the rust. Won't it eventually rust out, like an old car? Should I spray it to stop it from rusting, or adding vents enough?

Two important factors when ventilating the skirting.
1. Your Home Installation Manual gives you the proper ventilation formula, one square foot of free area, to each 150 square feet of floor space. One square foot equals 144 square inches.
2. Know the free area of the vent you are installing. You can not measure the vent to find out the free area. Some are marked, some are not. The everock vents are made in two different designs. The one with the louvers vents at 28 square inches, the one with no louvers, but with a fine screen vents at 72 square inches.

I have a 2300 sq ft home on concrete slab. The skyline manual says 1 ft vent to 150 ft floor space. If I'm doing the math right, I would need 90 of these vents with louvres, which is totally impractical. I will replace the 6 with larger, maybe 4 sq ft vents. Can you recommend any? Do I need to paint the frame to stop the rust now? Will it eventually rust out and the home will fall if I ignore it? This is my last post, thanks again for the helpful info!

2300/150 = 15.33 SF needed vent
144/28 = 5.19 louvered vents per SF (2 per SF with fine screen)
15.33*5.19 = 78.8 vents of the louvered variety,
15.33*2= 31 vents of the fine-screen variety.

We have a 2080 SF house on a concrete slab/block skirting with the usual perimeter-foundation set-in vents. I will count them and report back - I believe I have one about every 4-5 feet. I live in NW Oregon, in rain country.

The easy fix, is to remove the louvers from the vents you currently have, thus increasing the capacity to the 72 square inches each. This is easily done with tin snips. It is also important to have the first within 3 feet of the corner, so as to not have dead air in the corner.