Dark Gypsum Kalamazoo MI

The construction is 4-in. brick masonry walls with 4-in. concrete masonry backup. The interior has light gauge steel hat channels attached to the concrete masonry with rigid insulation between the channels.

R J Masonry
(517) 455-0099
1535 Linval St
Lansing, MI
 
Hane Tile & Plastering Mason
(734) 971-8298
2771 Lookout Cir
Ann Arbor, MI
 
Marcel Construction
(586) 757-8392
26242 Grobbel Ave
Warren, MI
 
Rose Tile & Masonry
(734) 662-8004
1917 Dunmore Rd
Ann Arbor, MI
 
Tozier'S Chimney Sweeping
(517) 372-7805
6141 Beechfield Dr Apt 203
Lansing, MI
 
B & D Drywall Supply Inc
(586) 463-7774
44700 N Groesbeck Hwy
Clinton Township, MI
 
Brother'S Construction
(734) 665-8109
1235 Astor Ave
Ann Arbor, MI
 
Hanneman & Fineis Concrete Construction Inc
(517) 371-4053
16101 S US Highway 27 Ste 6
Lansing, MI
 
All Pro Masonry
(586) 868-3860
4778 Dunkirk Ct
Sterling Heights, MI
 
Giannola Masonry Co
(586) 792-2070
35086 Cordelia St
Clinton Township, MI
 

Dark Gypsum

Provided By:

Source: MASONRY CONSTRUCTION MAGAZINE
Publication date: November 1, 2008

By Norbert V. Krogstad

What causes the dark vertical lines that occur on gypsum wallboard installed directly over the furring strips in brick veneer/concrete masonry walls?

The construction is 4-in. brick masonry walls with 4-in. concrete masonry backup. The interior has light gauge steel hat channels attached to the concrete masonry with rigid insulation between the channels. There is a vapor barrier over the insulation and hat channels. The gypsum wallboard is anchored to the hat channels on the interior face of the vapor barrier.

We were originally thinking that the problem was associated with leakage through the masonry. However, the building has large overhangs and during most rains the water doesn't even get to the brick masonry. Also, the vapor barrier would stop any moisture that did get in the masonry from reaching the interior wall board anyway.

How can this problem be avoided?

The darkening of the gypsum wallboard over the hat channels is sometimes referred to as “ghosting.” This phenomenon is typically caused by condensation from interior air during cold weather.

Because the insulation was placed on the interior side of the concrete masonry, both the concrete masonry and brick masonry are cold. The hat channels interrupt the insulation and are in direct contact with the cold masonry walls.

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