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jregier
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# Posted: 8 Apr 2022 01:50pm
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Hi everyone,
I have a few potential issues with my cabin in Whitestone Ontario and I am looking to get opinions if these are major issues that would justify a major rebuild or if these issues are fairly common with older cabins. We use the cabin on weekends, once per month on average (2 trips in the winter months). However, I want some confidence the cabin isn't going to fail while we are sleeping in it.
Issue 1: Roof Sagging / Rafters Bowing
The 2x4 rafters (true 2x4) span approximately 8' and some have a decent bow in them... presumably from the 1.5ft+ snow sitting on them all winter over the years. On the original cabin section, I measured around 5/8" deflection over 6' (I only had a 6' straight edge). I have only owned the cabin for 2 years... who knows how long the rafters have been bowed or if it's been like this since day 1. How much can these 2x4's deflect before they fail? The 8' addition is built with new 1.5x3.5" 2x4's and they are not bowing...yet.
Additionally, the roof is sagging approximately 3.5" over the 24' cabin length. Once I level the foundation I will likely be closer to a 2" sag. Perhaps it's always been like this. My gut feeling is this is not overly concerning and I will measure each year to see if it's getting worse.
Issue 2: Cabin Foundation Supports
My center cabin support (6x6 cribbing support in the picture below) looks like it is sinking into the mostly clay ground, around 1.5". Last year I installed this support, dug a few inches down for gravel and the earth was like jello... I lined the hole with landscape fabric, poured in a few inches of gravel, topped with a patio stone, and built up the wood cribbing. My plan was to replace all cabin supports this year using this method but am now concerned if this is already sinking. Is there a better method for clay ground with poor drainage?
Issue 3: Addition support posts being pushed in
The previous owners added an 8' addition to the front of the cabin and dug out the basement under this addition. The earth under the deck and under the old cabin is pushing into the basement on either side and the support posts are 20 degrees off vertical. I braced the two walls at the bottom to prevent the bottoms from kicking out. Also, there is currently 5" of standing water in this basement. Even in the summer the mostly clay dirt is very wet. I am unsure how severe this issue is...
At this point I am debating options... pending feedback from you guys:
1) Prefered option - Monitor the roof sag/bowing, brace the basement walls to prevent them from caving in any further, replace foundation supports with wood cribbing and relevel each year.
2) Build knee walls in an attempt to push the bow out of the roof / support the 2x4 rafters, dig on either side of the basement walls to prevent them from being pushed in and rebuild the walls, replace foundation supports with wood cribbing and relevel each year.
3) Determine the cabin will not last much more than a few more years, install wood cribbing supports to buy me a few more years. Start building a new cabin.
I will add some pictures so you can see what I am dealing with.
Thank you everyone in advance for your feedback!
Basement_wall_1.jpg
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Exterior_Roof_Bow.jp.jpg
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jregier
Member
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# Posted: 8 Apr 2022 01:51pm
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Adding more pictures
Basement_wall_2.jpg
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Exterior_roof_sag.jp.jpg
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Exterior_roof_sag2.j.jpg
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Interior_Roof.jpg
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jregier
Member
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# Posted: 8 Apr 2022 01:52pm
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and more pictures
New_wood_cribbing_su.jpg
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Old_support_sinking..jpg
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Water_in_the_basemen.jpg
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Water_under_the_cabi.jpg
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jhp
Member
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# Posted: 8 Apr 2022 03:21pm
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When you say "the basement" can you describe the whole foundation in more detail?
In the water picture (water_in_basemen.jpg) - what is on the other side of the interior wall? Or is that what is shown in basement_wall_2.jpg?
Is what is underwater just bare earth?
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Brettny
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# Posted: 8 Apr 2022 03:42pm
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What's the foundation blocks? This looks to be a borderline teardown job. 2x4 are less than adequate for any horizontal support becids a top or bottom plate. Once you reframe the roof and fix the foundation your really just left with a few walls you havent messed with..yet.
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jregier
Member
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# Posted: 8 Apr 2022 03:44pm
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When you say "the basement" can you describe the whole foundation in more detail? - I attached another picture sketching out the foundation, the 1/2 labeled correspond to the Basement_wall_1 & ..._2 pictures.
In the water picture (water_in_basemen.jpg) - what is on the other side of the interior wall? Or is that what is shown in basement_wall_2.jpg? - Correct, Basement_wall_1 & ..._2 pictures
Is what is underwater just bare earth? - Yes, bare earth
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jhp
Member
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# Posted: 8 Apr 2022 03:55pm
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I'm certainly not an expert so take this however you want:
I'm not sure I'd consider that structure safe to be in any more. It's pretty clear the ground is moving a lot but its hard to measure exactly how much. If you have a some dry seasons you might not see anything for a couple more years. If you have a wet season then I dont see it would take much to completely lose a corner of the foundation in the front by the basement unexpectedly.
Its probably the safest in the winter when it's frozen and late summer when it's totally dried out but the next couple months are going to be anyone's guess.
Short version - whatever effort you put into holding onto this thing is basically wasted...I'm not sure you win this foundation battle without picking up the whole structure and fixing what's underneath it.
I'd be planning a rebuild ASAP starting with a real dirt engineer.
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travellerw
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# Posted: 8 Apr 2022 04:28pm
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I'm surprised no one has mentioned the roof yet..
2X4 with no rafter ties and only a few collar ties. Its no wonder it sagged. I'm guessing it also pushed out the walls a fair amount.
Not even sure what to suggest to fix it. Maybe a support post that you can slowly jack up, while pulling the walls in with a come-along. After that you will NEED to install rafter ties, which means no open roof or loft. Lots of work!
I would agree the foundation should be first.
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ICC
Member
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# Posted: 8 Apr 2022 05:01pm
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Quoting: jregier Start building a new cabin.
Now.
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gcrank1
Member
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# Posted: 8 Apr 2022 06:09pm - Edited by: gcrank1
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I am not an engineer, just a practical guy.
The inadequately tied roof is sagging from the load making the walls bow out and the ridge drop.
The rafters are sagging because inadequate for the load even for that short span.
If you dont want the roof to fall in while you mess about with the rest you need to stabilize the roof with some eyebolts? thru to planks or beams outside (to distribute the stress) and come-a-longs? inside to somewhat slowly draw the walls back. Multiple, not just one.
At the same time you may well need some jack-screw post up to the ridge to work it up while you draw walls in.
The wood and connections need to adjust to this! as you go.
If you can get that squared away you put in ties to hold all drawn in and could maybe sister in 2x6s? on each 2x4.
Somewhere in the stabilized and in process jacking/drawing you could start squaring up the base because now the roof wont fall in while working on the bottom.
I think I'd just get better 'floating' pads under in case it turns out it just aint going well and needs to come down; ie, at that point 'foundation' work would have been a waste.
Btw, that looks like a 'crawl space' rather than a 'basement'.
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Cedar Fever
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# Posted: 8 Apr 2022 07:03pm
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Welcome to the poorly designed roof club. I am in the same club. Thinking of ripping the roof off, putting on sheathing. Yours seems to need reinforcement or build a solid roof on top of it.
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rpe
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# Posted: 9 Apr 2022 09:36am
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Foundation: That wet clay ground will be a challenge. Frost heave will be major issue, particularly with those floating cribs supporting the structure currently. Do the doors and windows open properly in winter? I'd imagine the building moves quite a bit. To sort out properly you'll need to dig down below frost line (or to bedrock), and build some proper piers. Once that is done, backfill around the piers with a generous layer of gravel or coarse sand, as that will help protect the piers from frost heaving and side loads.
Basement: Without massive effort, I don't see how that is going to last. Use the excavated space to build some support piers for the structure above, and backfill the area back roughly to grade level again with gravel/sand. Internal bracing for those walls as you've mentioned won't likely fare well against the forces of nature no matter what you try. Water+Clay+Freezing temps is a killer combo.
Roof: Now that the building is sitting on a stable foundation, pull the outer walls back straight, lifting the ridge. Rafter ties can then be added to get the power of the triangle working for you again. Alternatively, you might be able to forgo the rafter ties and install an LVL ridge beam in place, supported by posts at either end, and possibly mid-span as well. Engineering needed. Piers should be directly below the post locations to transfer the roof load down to the foundation. Once the ridge is sorted, rafters themselves should be inspected and reinforced. The sag mentioned sounds excessive.
Whether the building is safe for use is not a decision I'd take lightly. I'd imagine when it does collapse it will be in the winter under snow loads. These are recommendations from an unqualified fellow cabin-owner north of Parry Sound as well. Get to the piers quick as the window between frost-out and blackflies-in is only a couple weeks!
Good luck with the project!
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paulz
Member
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# Posted: 9 Apr 2022 11:06am - Edited by: paulz
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Call that Homestead Rescue guy. Should be good for a couple episodes.
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gcrank1
Member
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# Posted: 9 Apr 2022 12:27pm
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Unless you LOVE the exact spot that is sitting on, and LOVE that structure, imo, putting that much work and money into a proper set of piers under That particular structure is questionable.
How about tying the walls together so you stop the spreading (ie, 'stabilize' it so it continues to be usable) and start building piers where you want the New Cabin to be.
Build the new one right, move in, and use the old one as a toolshed/utility building.
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curious
Member
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# Posted: 9 Apr 2022 12:56pm
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jregier
Member
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# Posted: 9 Apr 2022 08:55pm
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Thanks all. Sounds like I should be going with option 3 (install new floating supports and start building a new cabin). If piers below frost is the preferred method I think we will be better off choosing a new location and building a new cabin. I imagine it will take a couple/few years to complete... in the meantime, I will replace the toppling foundation supports. I agree if the roof fails it will be in the winter so we will forego winter trips for now.
Regarding foundations, a couple questions:
1) What is the maximum size cabin you typically see on piers? If possible we would like to have another bedroom and small bathroom, 16x24 is the current size.
2) Pier diameter and spacing? Footing size?
If anyone has recommendations for books / online resources on pier design that would be appreciated.
I plan to take a few soil samples at various depths in May and try the glass jar separation method to understand soil composition. I dug an outhouse hole 3-4ft deep last summer and it filled with water about 6" below grade. I hope piers will stand the test of time if I build a new cabin.
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ICC
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# Posted: 9 Apr 2022 10:26pm
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Quoting: jregier I dug an outhouse hole 3-4ft deep last summer and it filled with water about 6" below grade.
And then what happened? Did the water stay? Did the level drop? Did it come back?
Was the pit usable for an outhouse?
And what is the frost depth?
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ICC
Member
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# Posted: 9 Apr 2022 10:29pm
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Oh! The water in the "basement" photo...... How deep, how far below grade is the top of the soil under the water? Is there usually water in that space or only at certain times?
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Brettny
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# Posted: 10 Apr 2022 06:03am
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Quoting: jregier agree if the roof fails it will be in the winter so we will forego winter trips for now. Regarding foundations, a couple questions:
You can help that the roof is sagging in the mean time by useing 2x4s the width of the cabin and connecting the top plates together..as if your putting a ceiling rafter in.
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jregier
Member
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# Posted: 10 Apr 2022 08:28am
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ICC - The hole dug for the outhouse the water level seemed to fluctuate. It was not usable... be ended up purchasing a composting toilet. Frost depth is 4'.
I came across these pin foundations last night, they seem to be a perfect product for my application (https://groundframes.com/how-it-works/#installation). My site is 6kms by ATV through a pretty rough/mudhole-ridden trail so bringing in a significant about of gravel and concrete will be a challenge. I will start a new post on this one.
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morock
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# Posted: 15 Apr 2022 08:29am
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You could call techno metal posts. They can get their machine in there and do some test holes. The clay may not be strong enough to support their piers, but they can drill the bedrock too. If the bedrock is not to deep they can put posts down. Their machine is small enough to get inside the cabin and locate posts through the cabin floor.
Might be worth a phone call.
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