From: Derek Lester
Sent: Monday, October 3, 2022 9:43 PM
Subject: Stevens Lodge Support Bean Repair
Gentlemen,
In cleaning out the basement, we removed all dirt and debris from around all the wood support beams. During this, we found:
1 beam completely rotted and holding no weight
1 is 2/3 rotted through
1 is wet all the way through
1 was placed on a brick that is 2/3 cracked.
I still must check a half dozen additional support beams.
Most of the main support beams are rough cut logs, not dimensional lumber
Near Term
I recommend we add additional support around rotted and suspected beams at one of our work parties this month (either this Saturday > or Saturday the 22).
Longer Term (Spring/early summer)
Call in a structural engineer to assess and recommend how to support the lodge’s foundation for the next 75 years.
I just wanted to get this on everyone’s radar. Adding supports this fall should be straightforward. It’s the long-term shoring up that we will need to talk about more.
What do you all think?
From: Tom Hansen
Sent: Tuesday, October 4, 2022 6:41 AM
Jeff et al-
I agree with your temp fix approach in general. If you send me pictures, we can discuss by phone if desired. Due to some things happening at home, I will not have time to come up and look myself right now, but I will be happy to do so at a later time. No need to hire a structural engineer as I am comfortable using my skill set to make at least an initial assessment. This is not the first time that this type of situation has come up.
From: Matt Simerson
Sent: Friday, October 7, 2022
Derek, great job on the housekeeping under the lodge, and noticing the issue. Clue 1 that we should have been looking further into foundation decay / erosion / settling was the floors in the bathroom being so far out of plumb.
I just wanted to describe what a permanent fix looks like in everyone's minds. Stevens has a continuous perimeter foundation with a supporting pier and beam running down the center. The beam is supported by posts on piers and the posts have eroded away. The builders probably didn't put an isolation membrane between the soil and post. (Better built buildings of Steven's vintage have a cut piece of shingle material between the post and the ground/soil/concrete footing.
Step 1: determine the extent of the settling. You all might have noticed that the stairs aren't level. The bathroom floor is over an inch out. Some of the top plates are canted inwards. There's abundant evidence of settling. We should get a laser level set up under the lodge, project a line all the way around the perimeter foundation and measure how close to true it is. The bad news: this might create a whole new project.
1.1: While projecting that level line, poke a screwdriver or ice pick at the sill plate and rim joists all the way around, testing how solid the wood is. There's a very good chance that sections of those plates need replacement.
1.2: Check the straightness of the top of the beam. There's a good chance that lacking sufficient support, that beam is now sagging. Check the integrity of the beam itself for any signs of rot and decay, and judge whether it can be sistered or must be replaced.
Step 2: drive a vertical stake near (~14" away from) each of the existing piers and mark it at the same reference height as the perimeter foundation. When doing shoring work next year, the stakes will prove useful.
Step 3: Run a load calculation on the building (using 284 psf as the Ground Snow Load). From there, calculate the beam size required down the center of the lodge, as well as the spacing and minimum pad size for the piers.
Step 4: I'm with Tom here, we don't need a structural engineer for this. Skip step 3 and overbuild it. Pour a series of 2' square pads with embedded 6" post bases. Do that between each of the existing posts. This year, put posts in for temporary supports. Next year, plan to sister the main beam, using the new pads as jack points with a few 20-ton jacks. Slowly raise that center beam to match the perimeter reference lines we set in step 1.
4.1: Each 24" post base starts with a 27" square patch of undisturbed (or compacted) native soil. Atop the soil is a 2x8" wooden box with a 24" inside measurement. Cut a piece of 6-mil plastic and line the inside of the box with it. Center a 6" post anchor in the box with the flat interface raised 1" higher than the top of the wooden box. Fill the box with concrete, smoothly sloping the top of the concrete down from the post anchor to the outside edges.
4.2: Bolt 6x6 posts in the post anchors and positively attach them to the beam with structural post caps.
4.BS: The Building Science: the 6-mil plastic prevents soil moisture from constantly wetting the concrete pier. Moisture won't hurt the concrete but it travel through the concrete (capillary action) and would cause the post anchor to rust. Rusting metal in concrete expands, breaking the concrete. The post anchors (weren't required when the lodge was built) keeps the support posts atop the pier blocks during seismic events. The 2' square piers each have 4 times the load bearing capacity of a standard 1' pier block. The sloped top of the pier blocks sheds any bulk water instead of letting it pool and wet the bottom of the posts. Post caps keeps the posts under the support beam during seismic events.
Step 5: With the building raised and supported on the new piers and posts, jack the building up another 1/8", remove the existing posts, and repeat step 4 for each of the original posts. When finished, lower the building, removing the jacks and dunnage and our center beam has roughly an order of magnitude more support. Keep a roof over the building and that support beam will last 500 years.
Step 6: If the sill plates or rim joists need replacement, jack up the perimeter of the building with temporary posts and beams and replace decayed wood as necessary. Add additional corner framing required to meet hurricane and seismic code standards and bring the knee walls and sills up to (or better than) current building code. Sill plates need 5/8" bolts added (or equivalent retrofits like the Simpson URFP). Every corner must have hold downs added (giant steel straps) with a 3/4" galvanized bolt epoxied into the concrete foundation walls. Then interior plywood (with vent holes drilled in) is added to the interior of the knee walls with a seismic nailing pattern. (These are rather "modern" additions to the building code, added after the Loma Proprieta and Nisqually quakes).
Jeff et al- I agree with your temp fix approach in general. If you send me pictures, we can discuss by phone if desired. Due to some things happening at home, I will not have time to come up and look myself right now, but I will be happy to do so at a later time. No need to hire a structural engineer as I am comfortable using my skill set to make at least an initial assessment. This is not the first time that this type of situation has come up.
Derek, great job on the housekeeping under the lodge, and noticing the issue. Clue 1 that we should have been looking further into foundation decay / erosion / settling was the floors in the bathroom being so far out of plumb.
I just wanted to describe what a permanent fix looks like in everyone's minds. Stevens has a continuous perimeter foundation with a supporting pier and beam running down the center. The beam is supported by posts on piers and the posts have eroded away. The builders probably didn't put an isolation membrane between the soil and post. (Better built buildings of Steven's vintage have a cut piece of shingle material between the post and the ground/soil/concrete footing.
Step 1: determine the extent of the settling. You all might have noticed that the stairs aren't level. The bathroom floor is over an inch out. Some of the top plates are canted inwards. There's abundant evidence of settling. We should get a laser level set up under the lodge, project a line all the way around the perimeter foundation and measure how close to true it is. The bad news: this might create a whole new project.
1.1: While projecting that level line, poke a screwdriver or ice pick at the sill plate and rim joists all the way around, testing how solid the wood is. There's a very good chance that sections of those plates need replacement.
1.2: Check the straightness of the top of the beam. There's a good chance that lacking sufficient support, that beam is now sagging. Check the integrity of the beam itself for any signs of rot and decay, and judge whether it can be sistered or must be replaced.
Step 2: drive a vertical stake near (~14" away from) each of the existing piers and mark it at the same reference height as the perimeter foundation. When doing shoring work next year, the stakes will prove useful.
Step 3: Run a load calculation on the building (using 284 psf as the Ground Snow Load). From there, calculate the beam size required down the center of the lodge, as well as the spacing and minimum pad size for the piers.
Step 4: I'm with Tom here, we don't need a structural engineer for this. Skip step 3 and overbuild it. Pour a series of 2' square pads with embedded 6" post bases. Do that between each of the existing posts. This year, put posts in for temporary supports. Next year, plan to sister the main beam, using the new pads as jack points with a few 20-ton jacks. Slowly raise that center beam to match the perimeter reference lines we set in step 1.
4.1: Each 24" post base starts with a 27" square patch of undisturbed (or compacted) native soil. Atop the soil is a 2x8" wooden box with a 24" inside measurement. Cut a piece of 6-mil plastic and line the inside of the box with it. Center a 6" post anchor in the box with the flat interface raised 1" higher than the top of the wooden box. Fill the box with concrete, smoothly sloping the top of the concrete down from the post anchor to the outside edges.
4.2: Bolt 6x6 posts in the post anchors and positively attach them to the beam with structural post caps.
4.BS: The Building Science: the 6-mil plastic prevents soil moisture from constantly wetting the concrete pier. Moisture won't hurt the concrete but it travel through the concrete (capillary action) and would cause the post anchor to rust. Rusting metal in concrete expands, breaking the concrete. The post anchors (weren't required when the lodge was built) keeps the support posts atop the pier blocks during seismic events. The 2' square piers each have 4 times the load bearing capacity of a standard 1' pier block. The sloped top of the pier blocks sheds any bulk water instead of letting it pool and wet the bottom of the posts. Post caps keeps the posts under the support beam during seismic events.
Step 5: With the building raised and supported on the new piers and posts, jack the building up another 1/8", remove the existing posts, and repeat step 4 for each of the original posts. When finished, lower the building, removing the jacks and dunnage and our center beam has roughly an order of magnitude more support. Keep a roof over the building and that support beam will last 500 years.
Step 6: If the sill plates or rim joists need replacement, jack up the perimeter of the building with temporary posts and beams and replace decayed wood as necessary. Add additional corner framing required to meet hurricane and seismic code standards and bring the knee walls and sills up to (or better than) current building code. Sill plates need 5/8" bolts added (or equivalent retrofits like the Simpson URFP). Every corner must have hold downs added (giant steel straps) with a 3/4" galvanized bolt epoxied into the concrete foundation walls. Then interior plywood (with vent holes drilled in) is added to the interior of the knee walls with a seismic nailing pattern. (These are rather "modern" additions to the building code, added after the Loma Proprieta and Nisqually quakes).