Hidden-Vent Calculator
Home length in feet.
www.DURASKIRT.com
25'
30'
35'
40'
45'
50'
55'
60'
65'
70'
75'
80'
85'
90'
95'
100'
Calculation ratio used = 1sqft of vent to 150sqft of crawlspace.
Home width in feet.
8'
12'
16'
20'
24'
28'
32'
36'
40'
44'
48'
3
5
6
7
9
10
11
13
14
15
17
4
5
7
9
10
12
13
15
17
18
20
4
6
8
10
12
14
15
17
19
21
23
5
7
9
11
13
15
18
20
22
24
26
5
8
10
13
15
17
20
22
25
27
29
6
9
11
14
17
19
22
25
27
30
33
6
9
12
15
18
21
24
27
30
33
36
7
10
13
17
20
23
26
29
33
36
39
7
11
14
18
21
25
28
32
35
39
42
8
12
15
19
23
27
30
34
38
42
45
9
13
17
21
25
29
33
37
41
45
49
9
13
18
22
26
30
35
39
43
47
52
10
14
19
23
28
32
37
41
46
50
55
10
15
20
25
29
34
39
44
49
53
58
11
16
21
26
31
36
41
46
51
56
61
11
17
22
27
33
38
43
49
54
59
65
52'
18
21
25
28
32
35
39
42
46
49
53
56
59
63
66
70
56'
19
23
27
30
34
38
42
45
49
53
57
60
64
68
71
75
Note: Ventilation is used for enclosed crawlspace only. Enclosed deck areas do not need
to be included in the crawlspace area.
Installing the hidden vent
Read the Hidden Vent Calculation Sheet and determine how many square inches of vent are needed.
HUD Code for Manufactured Homes is 1 square foot of venting for every 300 Square feet of floor space,
providing that a 6 mil. Black vapor barrier or 3 ½” slab is provided. (Note: it is recommended that you
vent the two long sides of the home for cross ventilating as per the code).
1st Recess panels below rim joist a minimum of ½” or what is needed to allow the free airflow that is
determined by the square footage of the home.
2nd Start setting the panels recessing them back form the belly-band the predetermined amount needed in
order to allow for the 1 square foot in 300 square feet of home.
3rd Install the Hidden Vent Screen so that it fits tightly against the bellyband and the skirting with a
minimum of one screw or nail at each end. We recommend overlapping them so that only one screw is
used at the overlap and that the joints line up so not as to allow more than ¼” x ¼” air space.