Attaching a Porch to a Monolithic Dome

The Airform is essential to the protection of the insulation and ensuring waterproofness. It should not be cut back, peeled, or damaged beyond absolute necessity. Holes made in the Airform for the bolts should be caulked with NP1 or other urethane based caulking.

The urethane foam under the Airform should be a minimum of 2 pounds per cubic foot which will give a compressive strength of 30 psi or 4320 pounds per square foot (PSF). Design loads should not exceed 3000 PSF. Loadings of 2000 to 3000 PSF are acceptable.

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The attachment device bolt, wedge foot, tapcon, Rawl spike, etc. should be firmly anchored into the concrete under the urethane foam. Monolithic Dome shells are usually 2.5 to 4-inches of concrete. Care must be taken to get the proper length of fastener. Another option is to drill through the concrete and use bolts with heads. In general we use a wedge foot concrete anchor.

Often we "pop" off some concrete on the inside that must be patched. This isn't a big deal but must be considered and taken care of.

Do not get carried away with the size of the anchor. Usually a ¼" or 3/8" anchor is sufficient. Most of these work well with 1.5" to 2" embedment.

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The "pad" should be of sufficient size to carry the load to the dome and stay within the specified loads. "Pads" can be steel or wood. If using wood, use treated wood or plastic wood to prevent rotting. Be sure it is stiff enough to resist pressure curling.

After "pads" are affixed, the overhang/porch can be attached.

After the porch is attached, a piece of Airform material can be "welded" or glued to the Airform and glued, caulked or affixed to the porch as flashing to prevent leakage.

This same system works for most items attached to a Monolithic Dome.

177 Dome Park Place - Italy, TX 76651
Tel (972)483-7423 - Fax (972)483-6662
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