I’m prepping my basement to be poured and want to “help” the concrete guys do the straightest pour they never thought they could do 🙂
My foundation is ICF (Insulated Concrete Forms) to which I want to attach a screed board along it’s perimeter (simple enough?).
My basement is 32-33 feet on the inside, more or less square. I have two main partitions in the center running front to back that make three sections Approx 14 feet wide at the sides with a center section (bathroom and closet) at 6 feet. To clarify, I have two long rooms to either side of a center section where the bathroom and closets are.
My questions are these.
Can I set a screed board in the sand, right where the partitions will be?
If I could do such a thing, should I use pressure treated wood in these center screeds? Would I need to use pressure treated along the outside walls? Can I use regular studs and wrap them in poly? My house is a bi-level and based on other houses in the area of the type, I don’t expect any moisture problems.
Andrew in Canada (EH!)
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Don't bother setting screeds. The finishers will set their own wet screeds. If you want, snap a perimeter line to the top of slab, and another parallel ine 4'-0" above the slab. The higher line is in case the top of slab line gets lost. I have never worked with ICF's , but imagine they do not require an expansion strip on them. On block and concrete walls expansion strips are nailed on to the top of slab.
I'm a finishing carpenter, have dealt with rollercoaster basement floors by these same concrete finishers. I will bother, it's my house and i'm Psycho :-) Snapped lines don't help at times, they snap them in every pour.
Learn concrete FF and FL numbers then spec them to subs with the RFB. If the subs don't know what FF/FL means, don't use them.
and Google for: concrete standard FF FL
If you can't tell a contractor what you want, you can't know what you'll get.
ICF's can be easy to screed to because you can screw your screed boards right to the forms (at least the ARXX forms, I've used).
When I lay out my screeds, I prefer to maintain a MAXIMUM of 10 to 12 feet just to make it a more manageable pull. (I'm 57 years old, so give me a break!).
Prelaying your PT as a screed can be a problem because it's likely you"ll end up with voids beneath the board. (Install it later with anchor bolts or a powder-actuated nailer).
The best thing to use for screed, IMO, are 20' lengths of 1 1/2" or 2" pipe set on hangars on stakes. The hangars (can't remember the name) are stocked at most masonry supply houses).
The two most critical things in getting a flat floor are in getting the screed boards level AND having your concrete guys have some input so the sequence of the pour is efficient and pre-planned. As you advance the pour, the screeds are slid forward and/or pulled out. Screed voids are filled manually, steel stakes are pulled and wood stakes are driven down or pulled out.
If you're using a pump, the pump guys are a good resource for layout because 1; they know how to keep their hoses out of the way and 2; they usually know your 'crete sub and what floats his boat.
yes you can spec F numbers it's what the big box stores do... but find'n a local guy that knows or has ever heard of em can be hard...
set your boards if they will be under walls i don't see a big deal... i think i'd use something rot resistant... i'd also float em...ie: have em on stakes and make sure concrete goes under em... then make sure ur finisher has a power screed with a screed board long enough to ride your screed boards and a trowel machine to finish it... and doesn't use a bull float... bull floats are for driveways...
maybe i'm nuts but i hate to see low & high spot in slabs since it takes so little extra to get em flat... guess when i use to hang out at this old welders shop as a kid he would alway talk about how he made em rip the slab out 2x because he'd spec'd it to be flat so he could measure off of it....
started out with nothing... and have most of it left
First of all, I can't specify or demand anything as I'm building the house through a builder. As it is, I'm getting a big cut on builder's fees and can do most anything I please in the place without asking. Last thing I want to do is get testy with demanding someone other than who they normally use, in this sense I can prod gently by doing the screeds, much like setting decoys for ducks, you force them to do what you want, and in this case, it's even easier for them to do the slab.
I did have in mind to float the screeds under the wall so concrete would be under them also. They slab would also rest on the concrete pads (4), so there would be good support throughout.
If you choose to use screeds, they are not left in the floor nor would they be nailed to the perimeter. The reason floor guys don't use the old wood screed method is due to the work in pulling the screeds and filling them in and hand troweling the surface. Most use "wet screeds" or pipe screeds. Wet screeds are basically piles of concrete set to height with a transit or laser. The field is filled in between. Some guys are very good with this method. They strike off the surface with long aluminum bars. Pipe screeds are set up on little "chairs" that can stay in the floor or be pulled as you go. This is when accuracy for both level and pitch are needed. If a customer put in wood screeds and expected most fooring crews to have ever used them or know how to deal with them, I would think again. Not many residential slab crews use screeding machines because you need strong screed forms and the extra work that goes with them. Crews have their own preferred equipment, if you set the forms too close or too far apart, their strike off bars may not work. You have to move the screed bar back and forth, a board on the wall would be useless, wood screeds would be set out 6" or more. Save yourself a big headache and find a good floor outfit and let them do it their way. Just tell them what you intend to due in the future and be reasonable.
Beat it to fit / Paint it to match
I'll second that. If I put in screeds for a flatwork pour, my concrete guy would pull them out and put in his own before the first truck showed. If you can't find someone that can do a good job, then you've got a big problem. Part of "GC'ing My Own House 101", I guess.
I work commercial projects, and we use 'pro' finishing crews for almost all of our flat work, and in general they screw up wet screeds on a regular basis. They are just going too fast to be accurate, laser or no. On the odd smaller job (typically anything under 1000 sq ft) where we place and finish it ourselves, we use pipe screeds. As several other posters have mentioned, I find pipe screeds give the most consistent results and are less disruptive. It should be a simple matter of talking to your finishing sub ahead of time and asking how far apart they like them and so on. That way you will keep the peace with the sub but still get the quality you are entitled to.
Lignum est bonum.