Throwing up a small utility building this summer with 16″ high foot wall. Forms made out of 2×8, or possibly ply & 2×4 depending on what’s in the woodpile and budget.
Is there any big reason to not re-use this lumber in the construction of my shed roof?
much thanks
From plumbing failures to environmental near disasters, OHJ staffers dish on our worst and best moments.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Sure you can use it. Before you set the forms, staple plastic sheeting around it. This acts as a form release and keeps the lumber clean. Form oil is usually used, don't use it as I am not sure if it will continue to give off vapors . I would put braces close enough together so the form doesn't bend to much. Makes it easier when you build the shed roof.
mike
Back in the early 70s we use to single form basements around here with 1x6 and 1x8s. Maybe sprayed some form oil on it if the builder was willing to pay for it. Mostly not.
Stripped the forms 3-4 days later and used it for sub floor and roof sheating. Even on the jobs where we used form oil, we never heard of a complaint about the smell. Course the house were a lot looser back then, and it took a little longer to frame them, so maybe that helped the oil evaporate before occupancy.
Bottom line, it's a shed. Forget the plastic, it will give him a sorry finish on his wall. He can use 1x or 3/4" plywood, and form oil, and reuse the lumber for his shed. The combination of hot weather and air movement will clean the oil smell out in one summer.
Dave
Guys, this great info!Let me elaborate. This is going to be a prototype for me to try out building and try out some technologies on my weekender property :-). The building will be timerframe, going on a rubble-trench, shallow-frost foundation with plastered strawbale infill. So this will be highly insulated and fairly tight. Trying to stay above 40° via passive solar upstate NY.Is there such a thing as organic form oil? I'm trying not to introduce anything that's going to give off chemical vapors. The plastic sounded good to me. Ultimately this will probably have XPS on the outside of it, and be plastered over that, so not smooth may be good. Hey which reminds me, how do I attach XPS to concrete? Will it stick if I put it in the form with the pour?Thanks again!
Organic Form Oil = Vegetable Oil ( or olive oil if you like the smell )
Greg
Which makes me wonder-what kind of coverage I can get from a can of PAM :-)
I can't say whether this stuff would be any better than vegetable oil, but there is natural form release commercially available.http://www.elmusa.com/products/specialties.htmlAround here, many contractors use 2x10s for forming up structural slabs and then dice them up for header material.
I get a LOT of form feet out of a spray can of Pam.Quality repairs for your home.
AaronR ConstructionVancouver, Canada
I cleaned up my form lumber and built the basement stairs from it. Waste is evil.
Andy Engel
Senior editor, Fine Woodworking magazine
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
I've always used a portion of the first floor 2x10x16' for forming footers.
Try to be careful not to cut to many, ones that do get cut will be headers or blocking.
Strip the forms as soon as possible, sometimes later in the day, scraped 'em clean with flat trowels and water.
EricI Love A Hand That Meets My Own,
With A Hold That Causes Some Sensation.
[email protected]
Hi Andy, I'm a contractor in Shelton, CT. I heard from my framer that Westport does not allow any wood that has been used for forms (with concrete residue) to be used in the construction of a home.
He didn't know the reason but I was thinking that the concrete residue could act as a condenser for water vapor. It's the only thing I could think of.
Also I have a question for you in Insulation techniques.
My guess is that Westport might not allow form lumber to be used because it offends their sensibilities <G>.Andy Engel
Senior editor, Fine Woodworking magazine
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
Most recent foundation forms I did we with 2x6 DF#2 and Simpson WT wedge ties. I reused the 2x6 as studs and top plates for the pony walls, and have a small amount left over for next time. I've never liked building plywood forms too much, there's a lot of bracing and stiffening required to get them to stay flat and not blow. I'm sure there are plenty of guys who can form way faster than me and would not agree.
I've never liked building plywood forms too much, there's a lot of bracing and stiffening required to get them to stay flat and not blow. I'm sure there are plenty of guys who can form way faster than me and would not agree.
Sounds like I'm one.
I use CDX, snap ties, and no strongbacks, only walers. Been told by more than one experienced concrete guy that my forms would never hold. Wrong. Bracing and stiffening? Nope, other than the normal bracing to ensure plumb. Stripping leaves me with a pile of CDX and a pile of 2x4s. Nothing is nailed together.
I learned solely from a book "Concrete & Formwork" ISBN 0-910460-03-5 when I encountered extreme difficulty finding anyone to construct the cast-in-place concrete walls for my house. Almost everything here was block at the time. After running the numbers, I realized strongbacks and long ties were unnecessary and greatly simplified my forming.
Unlikely orchardguy would be interested, but I use old motor oil for form release. No reason to reapply for each application of the forms. Did experiment with 6 mil plastic once, interesting concrete texture. I've also experimented with lots of other texturing methods. Old lumber was probably the best received, particularly with differing thicknesses. That retaining wall, with colored concrete, looks like a wood wall from more than 10' away. PAHS Designer/Builder- Bury it!
It looks like most of the discussion has centered around what sort of form oil to use. I really see no need to use form oil at all for a single use. I use form oil only when I want to use the forms over and over. I vote to save the used motor oil and the Crisco.
I dont even use form oil, just pull while green and scape.
What is the spacing on your snap ties?
What is the spacing on your snap ties?
I'm using 16 or 18/sheet. 18 if verticle. As we normally pour well over 8' walls (two pours) the top ties anchor the bottom for the next pour, which is offset 3". A verticle sheet would be 6 rows of 3 ties, 3", 24", 45".
Hope that's clear. I'm also very careful about concrete placing, making the truck, or pump, move around the forms at least twice. Around here, 6-10" slump is normal. My site gets 3" so we work a little harder.
PAHS Designer/Builder- Bury it!
I have mine at 16" centers starting 8" from the edge.4x8 sheets.
I know what you mean , I like to use a 4" slump . everyone grumbles but I hate soup. Infact I will not use one readymix co because two of there drivers will water the mix with out consent. One of them even got mad at me for asking him to move the truck.
So, another dinosaur using ancient technology! Do you use long tails and strongbacks? I like my ties to start closer to the edges to make blockouts easy. And when raising the sheets for the second pour, closer to the ends means I get 15 1/2' tall.
My drivers are always the same. Difficult locations that the readymix co. won't send novice drivers into. We get along great. Seems they don't often encounter jobs like mine. On the occasion they over-estimate their capability and need a pull, we don't mention it to management. And I'm careful to express my appreciation for their efforts.
Regarding slump, I've only done what I've read and what my engineer specified. Doesn't make much sense to me to try to second guess, but this isn't a standard foundation either. I actually had a concrete salesman tell me that any vibrating at all was a major mistake. That was on my first pour here.
My plan approver, when he learned who did the engineering, said I'd be about right if I used half the steel specified. "Great, which half?" Then he told me the decision would be mine. Right... the guy who knows nothing makes the call. Maybe I "wasted" $500 of rebar, with 240 tons of roof suspended over my head.PAHS Designer/Builder- Bury it!
I used this pattern because that is what was specified for the foam form system that I used. I haven't changed because it has worked so well for me . Haven't had a blowout like when i used to frame up forms with a lot less ties. (read cheapskate) . My foam forms were R-form useing the pink foamulaR250 sheets tied together with plastic spacRties and structural steel studs that were screwed to the foam with plastic screws then stifbacks snaptied at 32" centers.
I use the ssstuds on my ply forms now like with the foam . only I use the hexhead snaptiesonly on the 16"centers.
Ihave never had to do a pour with ply forms over 8' yet . Probably never will as I do mostly DIYwork . If I have to go over 8' I would dothe forms with the lego type foam blocks. But Dinosaur ? just half a dino. I like to try new stuff also. I use Daton/........ hexhead ties and wedges
tom....
is this the book....
<<<
1.
View Image
Construction Manual: Concrete and Formwork by T.W. Love (Paperback - June 1, 1973) Avg. Customer Rating: <!---->
(Rate this item) <!---->Usually ships in 24 hours
List Price:
$17.75Buy new:
$12.07
Used & new from $9.74
Mike Smith Rhode Island : Design / Build / Repair / Restore
Hi Mike, that's it. My cover's a little different and it was only 8 bucks, but I've had it awhile. I also got everything I could from the Portland Cement Association and the American Concrete Institute, but there was less "concrete" advice. The ACI booklet "Cast-in-Place Walls" helped a little. I wouldn't guess it's anything you'd need. At the time I knew nothing, and did it with 2 helpers who knew less than I did (hadn't read the books).
My first concrete wall experience was as a laborer in Denver, digging out a 4" clearance under the foundation walls (on piers). That was to allow the natural bentonite room to expand. 11 acres of apartment foundation walls. 3 of us. I still remember the blisters.
I was promised that CDX would never hold up, but I've found that 6 pours are no stretch. We don't do much to take care of them. Sitting out in the weather 365. We do oil both sides. Crankcase oil, especially from a diesel, is amazing. First use is always on a wall side that gets buried. Might not be what you want to put into one of your houses. LOL You just need more storage. I've got stuff scattered over several acres.
The client house I poured, he insisted on the whole 180 lin ft (x 8'/pour) in one pour, requiring 100 CDX sheets. And a BIG pile of 2x4s. Pretty sure I'm fixed with both, for life. I much prefer 20 or so yds at a time, less hectic. Especially as I'm always pouring where they can't use fully loaded trucks or it'd slop out on the way up. Usually only get 6 1/2 yds/truck.
Hoping to pour 100+ yds this summer. After I finish that copper roof with the translucent panels insert and the machine sheds with the remainder of the panels. Turns out copper pop rivets work great to attach the panels to the copper roof. Copper's more noble than the aluminum on the panel edges, so gotta be careful. PAHS Designer/Builder- Bury it!
I have lined my forms with visqueen before. I cut strips and folded it under and over. When I stripped the forms, the wood was still pristeen. The visqueen leaves a very smooth wall and normally grey concrete looks white. I like it. It is easy to feel the crack between the boards for your form ties. It didn't take that long considering I didn't have to wash the boards after or oil them before. I use a hammertacker with light gauge staples to hang the plastic.
I used visqueen on mine. The resulting surface depends on how much care you use. Get the plastic smooth and tight and you get a real nice surface. Let it wrinkle, and you get wrinkles. The used form lumber is perfectly clean and usable. I even used some of the ply for bench tops.
-- J.S.
I wopuld tend to think that any organic form oil would try to go rancid and feed bacteria, not something that you would want. There are silicone based sprays tho that are inert.
XPS can be gl;ued to crete after it cures with foam spray from a can or PL 300, but for such a small job, trying to tie it in mechanically would not be worth the trouble, IMO
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Depends. Included concrete bits can do a job on saws.
Also a lot of form lumber has been sprayed with 'form oil'. Sometimes just a modified diesel fuel. This can make the lumber smell like fuel essentially forever. Also if it ever catches fire it will burn ... well ... like wood soaked in diesel fuel.
For a distant out building storing nothing of importance this might make no difference. The oil might help keep rot and termites at bay. And if you ever get tired of your shed it becomes a nice bonfire with the touch of a match.
Might be a major benefit if your in remote parts of ND. Electricity out. Gas gone. Heating systems kaput. The family caught in a blizzard are slowly freezing to death. With his last remaining energy dear old dad struggles to the shed with his trusty Zippo. When the National Guard gets there to dig out the frozen bodies the family is discovered safe and toasty warm. Cooking weenies, roasting marshmallows and singing Kumbaya around the raging bonfire their shed has become.
Mom is a little miffed he forgot to back out her BMW but she will extract her due for the next twenty years or so. He will suspect, faced with her scorn or the costs of divorce, freezing to death may have been the the way to go.
Once upon a time, I had to repair a curb and I had some rather nice lumber and the office supply cabinet was open and I found a roll of 2" clear plastic mailing tape. So I was a genius and used that and the wood survived fine. Not only that, but also the concrete surface was extremely smooth.
In your case, I would use the visqueen suggestion but the idea is to prevent the cement from getting into the pores of the wood. Perhaps formica would do the same. Be sure to vibrate well.
~Peter
What if there were no hypothetical questions?
My parent's bungalow was built in 1932- you can the imprint of the cement coated subfloor boards on the foundation. When I started doing carpentry in '84 my boss made all his own forms then we'd brush them off and put them on them into the building subfloors, you'd think we were still in the depression. But really he liked the idea of being non-dependant.
If you want to secure the foam to the walls line the forms with it . Put plastic screws ,used in roof work , into the foam so that the concrete will flow around it,holding the foam secure . I don't remember the company I got mine from . I use them to hold structural steel studs on the foam sheets til I can get the snap ties installed. Maybe try ; Potter Form & Tie Co. 1 800 248 6163
Mineral oil or baby oil would not go rancid.
I'm sorry, I thought you wanted it done the right way.
This is a very good point. Petroleum oil is very stable and organically unattractive. I'm at the site in a couple of weeks and will PAM or perhaps PAM Olive oil (my wife's italian :-) some 2x and leave it outside. We'll see what critters, bugs, etc are attracted when left outside for spring.
I got some brass molds, that I use for concrete samples. That I coat with pam. after couple weeks I will clean the molds with muratic acid. The pam still does not come off. The mold will be concrete free but a coat of pam will still be on the molds
Universal Form Clamp out of Chicago makes a product called Bioform. They make it specifically for projects specified in environmentally sensitive areas. You'd have to find a local dealer 'cause they don't sell direct.