what are the steps to strengthen pier and beam (sometimes called post and beam) foundation?
i will be installing a 3-5 ton Rocket heated cob bench mass heater in a rambler home in the living room over 8' length of floor space that has no beams beneath it.
i was told "If you have a suspended floor, the extra weight will probably need additional structural support so your floor doesn’t sag."
my research suggests that to reinforce beneath this heater, we would add 1 or 2 6' 4×4 beams going N to S beneath the joists (which go E to W. these would be nailed into posts nailed into pier blocks which would support the beam which would support joists.
how do i know where the spot i need to reinforce is when i'm in the crawl space?
how much weight can floor w/crawl space beneath, support ? the rocket heated cob bench mass heater shouldn't be more than 135 lbs/sf. i asked the local code officials what weight the floor itself is rated for but they didn't give me a clear answer .
Best Answer
The new support structure with a beam that you are proposing sounds fine.
If you are concerned, then overdo it by doubling the materials for the beam, or placing a steel L-rod 3/8" thick around the beam. Using an L-rod will reduce the number of bolts that you need to put through it into the beam, and will add structural support due to the angle.
The more important thing to remember here is what the pier block sits on. If you have bedrock or a similar rocky aggregate under the house, then you may be able to safely rely on it not shifting or changing over time.
If it is just soil, you can expect that you will get some compacting due to the weight of the heater. Even if you are able to bring in a tamper and pack the soil, you can still expect that over time it will change through natural cycles in the ground. Instead, place the broad flagstones under the peers to distribute the weight.
Make sure that the flagstones are thick enough that the weight will not crack them – since the breadth of the flagstone is being used to distribute that weight across the soft soil. Do not use metal, as it will rust and deteriorate.