Even a small 18 inch dish can excerpt a lot of force on a dish mast. The mast must be secured to withstand years of wind loading. A dish mast installed on a traditional wood framed structure should be secured with 6 lag screws. Two in the center secured into a wall stud or roof rafter, and four secured in the corners of the mount.
When a solid wood beam or post is available, four lag screws on the corners are usually sufficient. When mounting to brick or concrete, four corner anchors are sufficient. Masts should not be attached with wood, sheet rock or sheet metal screws.
Only lag screws at least 5/16" in diameter should be used and they should be long enough to set at least 2 inches into solid wood. At least two lag screws in the middle of the mount should be set into a wall stud of roof rafter. 1/4" inch diameter lag screws should never be used, they can loosen over a few years resulting in a loss of picture with wind.
Image 5 shows a roof mounted dish mast using 6-5/16" lag screws and sealed with roof patch tar.
Some form of sealant should be used on all wall / roof mast installations. The only exception would be if the mounting service was treated wood. An appropriate sealant for the mounting service should always be selected. Using silicone sealant on a asphalt roof should never be allowed. If you read the instructions for the proper use of silicone sealant it says something similar to; "Apply to a clean, grease free surface". Asphalt roofing IS a grease surface. The silicone will stick to the rocks on the roofing, but will never form a water tight seal to the roofing base. For asphalt roofing, roof patch tar or a material designed for sealing to asphalt should be used. A good tar alternative is a pitch pad compound. The rubber/tar like compound acts as gasket between the mount and the roof.
Image 6 shows a unsealed roof mount with only 4 -1/4" lag screws installed. This particular install was only 6 months old and was already loose.
Image 7 is a typical wall mount. The sealant is placed between the siding and the mount. Excess sealant is removed. This particular sealant will dry clear. Notice the 6 -5/16" lag screws securing the mount to the wall.
Ground post should always be metal pipe. Wood post not secured at both ends can twist as they cure and with seasonal changes. The dish in image 8 had to be realigned after 6 months. The wood post twisted enough to lower the signal level to the mid 40's. The dish in image 9 will never need to be aligned due to mast movement. All ground post should be set in concrete. A pin should also be inserted through the pipe to eliminate the chance of the pipe turning in the concrete. All ground post installs are not considered part of a basic or standard installation. Additional installation fees will be required. Never allow your installer to simply pound the pipe into the ground. It must be in concrete or a special pole designed for a cement-less installation.
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