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Lakeside Cottager
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# Posted: 11 Aug 2011 12:14pm
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Hello,
I have a lakeside cottage, 20X24, on a slanted lot. A few years ago I had the cottage raised and left sitting on cribs made of 4 ft long railroad ties. I would now like to get rid of the cribs and put another kind of support. This cottage is for summer use only and is not accessible during our cold Canadian winter. It sits about 16 in. off the ground at one end and 5 ft. a the other end. Would poured and reinforced cement slabs approx. 24 in. sq. combined with 6 in. cement pilons be suitable for a summer cottage where frost heaving is not a concern?
Lakeside Cottager.
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Just
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# Posted: 11 Aug 2011 08:05pm
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Need more info ,,, a pic or two of the cabin and a little more info and you should get some folks to help !!
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Borrego
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# Posted: 11 Aug 2011 08:38pm
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Are the 'slabs' really footings? And are you going to have posts coming off the footings with girders running horizontally?
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Lakeside Cottage
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# Posted: 13 Aug 2011 02:51pm
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The slabs will actually be footings. The posts will be coming off the footings. On the top of the posts I will have metal adaptors to reach and hold the horizontal girders. When everything is in place, I am planning to remove the cribs.
Make sense?
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Lakeside Cottager
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# Posted: 13 Aug 2011 03:15pm
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As suggested by Just, these are pictures of the cribs (there are a total of 6). I have since added a veranda.
The cribs currently support girders at each end (which are placed approx 24 in. from the end the cottage), and a central girder.
Hope the pictures help clarify.
View of existing cribs (while I was building the veranda)
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Cottage with added veranda
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Malamute
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# Posted: 13 Aug 2011 06:57pm
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If it were me, I'd use larger concrete piers. Check with the sonotube company and see if they have any info regarding sizing of piers for that application. Freestanding like that, I don't think I'd do less than 10 or 12". You can also get footer forms that go on the bottom of the sonotubes. If getting concrete brought in, it makes it in one pour, instead of two. If hand mixing it, and you have the time to do it in two steps, it probably doesnt make much difference. Where I am, I use the bigfoot footers, it save me mileage and small load fees on my concrete, and saves time.
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Lakeside Cottager
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# Posted: 13 Aug 2011 07:20pm
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Thanks very much for your input, Malamute. I will look into the into the footers as you suggest.
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Just
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# Posted: 13 Aug 2011 09:25pm
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Looks like lake huron shore line,, if not i am sure it is very unstable soil . not bed rock ! for that reason i would dig at least 4, 2ft. by2ft. holes, deeper than the frost line,, under each beem; i gess that would be 16 holes !!pour 12 in. of cement in each hole.. from there up i would use p.t. 6x6 because no matter what you do that thing is going to move .you will need lots of x bracing between each 6x6 do not skimp !! back fill each hole with crushed stone ..you will need to devise some method of jacking and shiming it when it dose move .as i am sure it dose now,and will again!!
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Malamute
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# Posted: 14 Aug 2011 12:06am - Edited by: Malamute
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There's a couple brands, one is called "Bigfoot" footer forms, I don't recall the other one. They are sized for a range of sonotubes, you cut off the smaller size rings than you need and screw the sonotube to it with drywall screws. They work great. The ones for up to 12" tubes cost about $34 ea I think around my area. Not cheap, but they do save a lot of time and trouble, you can dig, set the footer and tube in place, backfill in one operation, pour, and the next day strip the cardboard above ground off and you're done. I bang on the sides of the tubes after pouring to get the air bubbles out and trowel them smooth on top. I usually drop a couple or more pieces of rebar in after pouring also (precut to a few inches less than the height of the tube/footer), and use steel strap for anchors, depending on what I'm doing. On larger ones (18"), I premade rebar cages with horizontal rings of rebar also.
While digging the holes, if you set one, carefully backfill a little with a shovel to keep it in place (I like to pretty much cover the footer, as we have a lOT of rocks here), then one person holds on to the tube and has a level as it's backfilled, and your excavator digs the next hole, backfilling the one you're in as he goes. Saves time as well, and you can deflect the rocks as they come in the hole so they don't beat up your form. You can tweek the tube a little as it gets backfilled by which side you put the dirt, and pulling on the tube some as it backfills.
I make them a little longer than I need, and before pouring, fine tune the height with a laser level or transit. To cut them square, I measure from the end, and mark them every few inches around until I have a ring of marks around the tube and cut them with a sawsall with a long blade. I don't let the tip of the blade go in the tube, I think they cut straighter that way. If you can keep them pretty square they are easier to work with.
Here's two diffent makes, the black one is a bigfoot, I don't recal the make of the other. Black is for up to 12" the orange one is for an 18" tube.
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Lakeside Cottager
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# Posted: 14 Aug 2011 10:24am
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Thanks so much, Just and Malamute. Wow, I never thought I would get such good and clear feedback. A picture does paint a thousand words!
The cottage is located in the Ganineau Hills in western Quebec, and Just you are correct, the soil is unstable as it is gravel. Having had a septic tank put in 2 years ago I saw that the gravel is very deep -- there was not any clay within 6 feet. But there are lots of rocks, some pretty big ones too!! For that reason, I am concerned about digging 2 ft. below the frost line. Where I am, that would mean digging approx. 6 ft.
Since I will be working under the cottage, if I go with the sonotubes, how much should I extend the sonotubes/piers? That is, should I extend them as high as I can that will allow the pouring of the cement, or could I extend them perhaps half the length, put a metal bracket on top of the cement and then a p.t. 6X6 up to the girder with lots of cross-bracing?
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Just
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# Posted: 14 Aug 2011 11:46am
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could go with cement and tubes to just above the ground then wood . i'm just thinking that if things'' move ,, the wood can stand that a little better than brittle cement. if you are not going to the frost line i would for sure go with Malamute's plan as the smooth edges and plastic will resist the frost much better . aaa Ste.Agathe many great memories there!!
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Malamute
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# Posted: 14 Aug 2011 12:05pm - Edited by: Malamute
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We go 4' below grade here to avoid frost heaves, and 6' for water lines. Check and see what contractors do for foundations to be below frost line in your area.
You could do either, full concrete pier or partial. If it's not going to require heroic measure to get taller piers formed or mixed, I'd go as tall as reasonable. If going shorter, I think I'd go with a little larger piers.
Are you where a concrete truck can get to your site, or are you going to mix it yourself? You may need a pumper for a concrete truck to get it into your pier forms if very tall, unless the truck can get above the forms. If mixing your own, I'd be sure to finish each as you go, and not have a cold joint in your pier
You can use an extra footer form for a funnel when pouring also, if it's hard to get the shute just right.
If doing part concrete, part wood, you may be able to find an adjustable bracket, or have some made. The ones I've used for posts in log cabins were made by some welding shop, I bought them from another log builder that had them made. Don't recall exactly what materials were used, I may have some info around tho. Had about a 5/8" or 3/4" allthread welded to a square plate with another plate or large washers above with a nut to adjust. The post had a hole and just set on the adjuster. Making something that would anchor into the concrete would be good, and easy to do. Perhaps a piece of angle on top to have two surfaces (bottom and a side) to anchor into your beams above, or make a channel that would fit around your beam.
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Lakeside Cottager
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# Posted: 14 Aug 2011 03:07pm
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Again, great information. You gentlemen are great for my confidence.
Wonderful skiing around Ste. Agathe, though I am closer to the Ontario border near Wakefield, Que.
I will check the home building center this week to see what they have for a bracket or base to anchor the wood to the cement, and also check for footers. Going with larger piers does make a lot of sense. Is there any reason this larger surface could not also serve as a base for a hydraulic jack should I ever have to replace or adjust the wooden post?
Unfortunately, a concrete truck could not get to the back of the cottage due to the septic system and many trees in the way. I will mix the concrete myself with an electric mixer, and complete one footing/pier at a time as you recommend.
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Malamute
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# Posted: 14 Aug 2011 04:17pm
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A call to the concrete people and ask about a pumper may answer some questions if it may or may not be worthwhile. Self mixing will save money, but will take some time.
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Just
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# Posted: 14 Aug 2011 07:43pm
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good idea for the jack and shim mantainance of level .I always say you need the floor to be level on those nights when you need something level !!
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Just
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# Posted: 14 Aug 2011 08:04pm
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just a thought , if you are hand mixing 1 at a time could you not use the mold over and over till done .just trim the plastic to fit the outside of the tube insted of the inside ???????
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Malamute
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# Posted: 14 Aug 2011 08:22pm
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It needs to be backfilled to hold it in place, tho you could stake it down and brace the tube form.
I've heard of disasters when the footer wasn't secured, and had one blow out when it wasn't backfilled or secured adequetly. I just backfill to finished grade when I use them, so they will be in exactly the right place when you pour, but it may be possible to reuse them if on a very tight budget. You bought the concrete if it goes good or bad tho.
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Lakeside Cottager
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# Posted: 14 Aug 2011 08:41pm
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Using the footer over and over till done is a great idea.
I will enquire about a pumper. I don't know, but it could turn out to be a workable solution in my case and maybe not very expensive.
I really want to express my gratitude to you both (Just and Malamute) for taking the time to provide all the advice, ideas and picture. This is truly a worthwhile and enjoyable exercise.
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Malamute
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# Posted: 14 Aug 2011 09:10pm
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If you use a truck, you'll want to get footer forms for each tube so you can get them all ready and pour all of them in one shot. If doing it that way, I'd definately backfill them all, then no worries about them moving, and it will be easier to get to the top of the form to pour. If doing your own mixing, you may be able to reuse the form, since you'd just be doing one at a time, but it would still probably be easier to work if it was backfilled, so I guess you choose your work, buying forms, working around the unbackfilled tubes, or digging them back up to save a form.
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Lakeside Cottager
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# Posted: 15 Aug 2011 02:00pm
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I know when I start the work I will want to go with what is safest. The footings aren't that expensive when it comes to my safety or the possibility of destroying the cottage.
Come to think of it, having to dig up the footer each time may not be that cost efficient if I factor in my time and possibly the $$ of a helper.
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