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.

A Ct
(586) 772-1660
25530 SchoenheRR Rd
Warren, MI
 
Omega Construction & General Repair
(734) 665-8154
4042 Ann Arbor Saline Rd
Ann Arbor, MI
 
Brother'S Construction
(734) 665-8109
1235 Astor Ave
Ann Arbor, MI
 
Expert Construction Co
(586) 293-0920
31056 Shawn Dr
Warren, MI
 
Stillson Masonry
(616) 454-7540
1227 Houseman Ave Ne
Grand Rapids, MI
 
Silverado Construction Inc
(586) 758-2600
2055 E 9 Mile Rd
Warren, MI
 
Rose Tile & Masonry
(734) 662-8004
1917 Dunmore Rd
Ann Arbor, MI
 
Northeast Solite Corp
(810) 232-3088
1071 E Grand Blvd
Flint, MI
 
Alpha & Omega
(517) 349-8660
3654 Okemos Rd
Lansing, MI
 
Sivosky Steve
(810) 732-4490
6131 Mapleridge Dr
Flint, 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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