Good morning, all!
I am designing a new home and would like to use wood trusses for floor joists to span a larger space. It is my understanding that the wood truss should NOT be sitting on concrete – I assume that is because of the threat of moisture over the long term. So, what can I use between the concrete basement wall and the wood truss? Besides the obvious 2 x lumber, can I use 7/16 OSB? Or how about simply using 10 mil plastic sheeting?
Would appreciate your thoughts. and thanks!
Regards,
Tachi
tachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
Replies
You know, I had a guy about 12 years ago who was building his own house, and wanted to set the wood floor trusses directly on the concrete.
So you're only the 2nd person in 20 years that I've heard of who wanted to do that.
Honestly - My feeling is that if you know that little about construction you have no business designing a house.
Nothing personal...
Sorry, but I think you missed my question. I was asking for advice on the kind of materials that can be used to separate the truss from the concrete. I do lack the experience, but while it is still on paper, it is easy to fix! So, that is why I am asking about it now.
Regards,
Tachi
tachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
2x PT lumber bolted to the foundation is the typical detail.I might agree with Boss on this one...
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Boss is right. If the house is designed correctly, this question never comes up. Stick to your day job and let an architect design the house.
DG/Builder
Gentlemen, isn't it the idea of this forum for the less experienced to gain the knowledge of others? How does someone learn anything if his questions are answered with criticism and negativity instead of pertinent information?
The OP asked an honest question and look at the answers he gets..
Suppose an architect detailed the connection this way, and the OP is questioning it..
Suppose, like in BossHog's area, there is no need for an architect/engineer since there is no building dept..and the OP wants to do it right..
Come on people...that' not what this site is about...
Gentlemen, isn't it the idea of this forum for the less experienced to gain the knowledge of others? How does someone learn anything if his questions are answered with criticism and negativity instead of pertinent information?
Yes, that is one of the uses of this forum. You have to admit that the PT sill plate is a universal detail for residential construction. One may wonder what other details are not known by the OP.
Suppose an architect detailed the connection this way, and the OP is questioning it..
If an Architect called for trusses directly on the foundation wall I would question his abilities as well.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
I agree - To a point. Certainly we've all come here to learn. But someone with as little knowledge as the OP has isn't going to gain enough knowledge to design houses by asking a couple of questions here. Part of knowing how to design stuff is knowing when you're in over your head. Or knowing that there's reason to question something. I don't believe this guy is that far advanced. So I stand by my original observation.
Q: What do your boss and a Slinky have in common?
A: It's fun to watch them tumble down the stairs.
Point taken, Boss..and perhaps I was giving the OP more credit than I should have..
I have always believed that it is better to have someone come to the conclusion on their own that they don't know everything and should ask for help rather than tell them that they don't know squat..
So maybe the OP will muddle through a design and have either an archy or BI show him the error of his ways..and figure out why we design professionals get paid what we do..
Give the guy a break. Thirty years ago, when I was young, foolish and poor, I decided that building a house couldn't be too difficult, so I did it. It was literally the first thing I ever built (if you don't count the bookcase made of boards and concrete blocks).
I still can't build a chair and I have developed great admiration for professional builders. Nevertheless, the satisfaction one gets from creating a home of one's own is hard to match. The house I built has a million defects in design and construction, but it is still standing and keeping the rain and snow off the heads of the current owners.
I live in a 200 year old house, almost certainly built by another clueless amateur. It's still a pretty good house.
One probably could get by for a hundred years or so in Tucson putting trusses directly on concrete, and probably hs been done, Taschi may have seen a few like that. Some of the old bldgs there have untreated D Fir round beams out in the weather that are older than I am -- I tried that once in Seattle area and the D Fir lasted about 5 years!
Pretty sure Tucson has a bldg dept, so they should catch anything eggregious??
I'm not trying to trash the guy, or give him a hard time. My thinking goes more like this:If the OP doesn't know that you need a treated wood plate on concrete, what other general info doesn't he know that we all take for granted?ie: How much clearance do you need for a washer and dryer?Why do you need a 2X6 wall behind a toilet?How wide should hallway and/or stairway be?How big should doorways be for bedrooms, closets, bathrooms, etc.?What kind of electrical service do you need to your stove, washer/dryer, dishwasher, etc.?And this is just the beginning - Not even touching on structural issues. There are a million details to consider in designing a house. Forget something, and you're bound to have problems.
Q: How can you tell a woman is really ugly?
A: A cannibal takes one look at her and orders a salad.
I used this fourm about 3 years ago to get info on how to build my house. I and a friend built it from the footers to the peak , wired it ,drywalled it trimmed it floored tiled it. Never done it before it is 2900 sqft single story on a 2900 sqft walkout basement +900 sqft threecar garage he truss package had over 153 trusses in it with 100 differnt trusses. I had never built even a shed before. It was a wicked learning curve. I read over 2 dozen tauton books learning every type of construction from laminate to tile. And Asked alot of questions on this fourm And got alot of help I could not have done it without you guys. THANKS THANKS THANKS
Jim III
tzzzz, what will it be next:
Check out theAmerican Journal of Medicine and do your own operations?
Nah i like webmd actually and now i own all these saws hmmm............ Hey I just wanted to point out when posters give a solution as opposed to flame what postive things can happen.
Jim III
Some of the old bldgs there have untreated D Fir round beams out in the weather
Not just that, but laid in mud to fuse with the adobe. Then, vigas, (joists of a sort) go across those, to create a finished bottom to what until more modern tiems was a sun-baked adobe roof. The entire system was designed to keep moisture away from the bearing lumber framing.
Not something I'd likely try in the PacNor'Wet. <g>Occupational hazard of my occupation not being around (sorry Bubba)
Not to rock the boat or anything, but they do make hardware for this.
I've never used them or seen them used, but they do exist. I'm guessing they're more for commercial application.
http://www.uspconnectors.com/pdf-full-line-2005/Searchable_Menu_PDF/161.pdf
http://www.uspconnectors.com/pdf-full-line-2005/Searchable_Menu_PDF/162-163and218.pdf
Suppose, like in BossHog's area, there is no need for an architect/engineer since there is no building dept..and the OP wants to do it right..
That's precisely why we discourage him. He is not proposing to build a chair here. He is likely to design and build a house badly. Suppose he then sells the house and 5 years down the road it collapses and kills someone. What if that someone is one of your loved ones? Would that change your view on the matter?
In BossHog's area there may not be a LEGAL REQUIREMENT for a professional, but there still is a NEED for one.
DG/Builder
I think some of this speculation might be going too far. It seems that you guys are imagining the OP sitting at a drafting table getting plans ready for a house that will be built starting next week, without the intervention of a professional designer, plan checker, contractor, or anyone else.... that somehow he'll build this horrible monstrosity that contains so many errors as to be a public hazard.
My perception was that he's sitting there trying to get some ideas together that will be run thru someone else, someone with professional qualifications. Until we find out that this is NOT the case there's no point in jumping to conclusions.
It seems that you guys are imagining the OP sitting at a drafting table getting plans ready for a house that will be built starting next week
No, David, actually I am imagining a guy in shorts and loafers sitting with a poured foundation, no plans and a bunch of trusses laying on the ground next to it. The caption reads "Hmmm... I wonder how these things go on top of that..." :)
DG/Builder
I suppose it could happen. Maybe I'm just an optimist... I'm imagining him with a set of approved plans with engineering and a half-decent contractor working with him. I get people all the time who have done some research and HO-style 'design' who then defer to me for the details.
To be fair, we should mention to the OP the possibility of top-chord bearing floor trusses, and/or hangers to get them down flush with the mudsill!
You got it right, David. I figure I have about 5 years before I can retire; have wanted to build a home of my own for 30 years or more, and have the time and energy to start on the planning now. I know and acknowledge there is a lot I need to learn. That's one of the reasons I go to this forum. Secondly, with the detail advantages of a software like Architectural AutoCAD, I can design in phenomenal detail, and make changes as I pick up new ideas. I also have a lot of practical knowledge - have designed and installed complete kitchens and bathrooms, and done quite a bit of commercial electrical work. But I have not actually built a home, yet.
I sent an earlier response with a screenshot of a portion of the basement walls drawing. It shows a 2x6 sill plate for the SIP's I intended to use. I wanted the floor trusses to be INSIDE the insulated walls, and was looking for a way to avoid the double-sill plate.
Thanks for your support, at least!!
Regards,
Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
you can use special floor joist hangers which are attatched on the top of the wall and then hang down on the inside. Hard to get though. If you install woodjoists in metal hangers do not forget to use glue in the hangers to prevent squeaking. Nailing or screwing alone will not do.
I have designed and build custom homes for the last 30 years. Would be glad to answer questions you might have. You can contact me at [email protected]
Nothing special or hard to get about top-hanging joist hangers. They make hundreds of them every day. I order them like any other joist hanger and they show up on the job.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
How do YOU fasten them in ICF topsurfaces?
In that sort of location I use a 2 x 12 mudsill.I did like the look of the specialized one mentioned above though especial for ICFs
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Mind if we contact you also with a few questions. Our small town had lost the building inspector so there is no one to ask right now. Still stumbling on the procedures on how to frame from the block step foundation to the floor joists. Do I need to use double plates? things like this. Is there a detail anywhere that I can download.?
thanks for your help
can you provide a drawing of what you have?
What kind of soil are you building on? What size is the foundation wall. What does it consist of? How high is the wall? How is it anchored into the foundation? Are the blocks filled? What kind of home structure, single storey, double? What kind of backfill?
Yes I can e-mail drawings and answers to you tomorrow.
thanks.
looking forward to them
Sorry, Im not ready to send yet, but shortly. thanks again
Boy! You guys can be really hard on a guy! I was trying to keep my message/question short. Guess I shouldn't have. I am an electrical engineer with a LOT of experience, but not with home building. Some things seem logical, but I need to verify it. I presumed wood truss on a concrete wall would be a no-no, but had to ask about it.
I have attached a screen shot from my ADT2006 drawing of the basement walls. I am using ICF foundation walls, and wanted to convert directly to SIP for the main floor by attaching them to the 2x6 sill plate. That is, I didn't want to break the insulation link by installing the flooring on top of the foundation wall, and then installing SIP's on top of the floor. I was hoping to avoid doing a double sill plate: that is, a 2x12, or 2x10 on the bottom so that there is enough of a ledge to sit the trusses on, and then another 2x6 on top for the SIP's.
So, I guess I got my answer, as painful as it was!
Regards,
Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
Tachi - don't stop there - ICFs are a different animal - your best practice will be to use the ICF system from Simpson:
View Image
These are the exact hardware for your application. The ICFLC is embedded in the concrete when you pour. The ICFLC-W then screws your ledger to the ICFLC when you are ready to frame. Your I joists, floor trusses or joists will then be in joist hangers. The insulation envelope is preserved. (but I'd skip the sips and take the ICFs all the way to the eaves, personally)
I used this system on my house - it is really the greatest, and the building dept likes all the documentation Simpson provided.
Treat every person you meet like you will know them the rest of your life - you just might!
That's perfect.
Hey, Tachi, I suggest you get a couple of books. Rob Thallon's 'Graphic Guide to Frame Construction" and the JLC 'Field Guide' are two good ones that apply to stick building, and may be somewhat useful to you. There are doubtless specific ICF and SIPS books that others can recommend. For me there's nothing like a book full of drawings to help me figure stuff out.
There are doubtless specific ICF and SIPS books that others can recommend.
google "prescriptive manual for ICFs" and you will find a free PDF with details, load charts etc from HUD.
Treat every person you meet like you will know them the rest of your life - you just might!
Have been reading this thread with much interest since my search for information on framing on a block step foundation is not going to well. Can you tell me if the books mentioned give a detail of the proper procedure on how to build on a step foundation. I am a fine finish carpenter by trade and will be framing our cottage this summer but cannot find any information on this . I have posted a thread earlier but received only one response. If you have the books can you let me know if these details on in them, I have seen these on the net but have hesitated to purchase since this is the only info I need.
Thanks for your info.
There may be a way to hang the floor trusses from the mudsill with ICFs. I don't know, ICFs are very unlikely where I am and I've only actually seen one house using them. However, with conventional stemwalls we hang the floor joists all the time, so that top of joist = top of mudsill, and the subfloor is right on top of that. Total buildup from concrete = 2-1/4" to 3-5/8" depending on mudsill and subfloor thickness.
Typically, there is a Pressure-treated sill plate (usually a 2x6) that runs the perimeter of the foundation and is bolted down to the concrete.
The floor joists/trusses would then be nailed down to the sill plate..
OSB is not a good choice as it will rot in the presence of moisture...
> Typically, there is a Pressure-treated sill plate (usually a 2x6) that runs the perimeter of the foundation and is bolted down to the concrete.
That was typical, and a good idea, back in the CCA days. Now that PT is corrosive ACQ, perhaps a metal or synthetic barrier followed by a redwood 2x6 would be better.
I must agree with Boss Hog that this OP has a substantial learning curve between him and the place where it would make sense to design and build a house himself. Skip the learning curve, and he'll make some very costly mistakes. So, what's the best, most efficient, way up that curve?
-- J.S.
In our area, 99% of the houses use a 2x6 sill that is bolted about every 6 feet to the foundation. Inbetween we use a sill gasket, it comes in 50 foot rolls 5.5 inches wide and is about 3/16 thick and as you crank down on the nuts it compresses.
Best of luck with your house!
Have a good day
Cliffy
Cliffy,
Do you recall the brand name or source for that sill gasket that you use? And does it protrude out of the sides of the sill plate as it is compressed? I plan to attach an SIP to that sill plate so there is little tolerance for extra material at that point.
Thanks.Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
I just looked at a roll today. It came in a clear plastic bag with no name on it. When it is installed and the acnchor bolts are tightened and the mass of the house is on top it only spreads out in its width marginally. A practice that seems to be catching on is to put a layer of house wrap under it too. Then later when the rest of the housewrap is installed, the top is tapped over the bottom. Sorry I couldn't be of more help to you.
HAve a good day
Cliffy
Tachi, I framed houses in Michigan for about 6 years before I ever saw my first mudsill. In those days, we set the dimensional lumber directly on the concrete. That wouldn't be allowed nowadays, but I'd be willing to bet that a susbstantial vapor barrier would suffice.
You probably won't get a definitive answer here because most poster here are conservative (I don't mean that in a political way) conventional (I don't mean that with regards to trusses vs dimension lumber) builder's. As such, they tend to shy away from anything that strays too far from the norm.
I would not hesitate to install lumber directly on concrete provided that I met the minimum protection to prevent moisture absorption. Obviously there would have to be some special circumstance surrounding and installation like that becauase there really isn't anything faster than laying down a simple sill plate. I suspect that you might object to using poisonous products in your home, which I tend to agree with. I would seek an alternative to if I were building a new home for myself.
blue
Hi, Blue, and thanks. I was wondering if maybe heavy on the plastic sheathing would not be sufficient. I had heard somewhere that sillgasket does not have a long lifespan. I had also intended to run at least 10 mil moisture barrier with low-density foam under the whole area, on top of the ICF, and was hoping that might be sufficient barrier between the truss and concrete.
Regards
Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
> I had heard somewhere that sillgasket does not have a long lifespan.
I guess it depends on the quality of the gasket. Here's a company from which I've bought some excellent long lasting products, though I haven't yet needed their sill gasket. I'll probably try it on a little gazebo job when I get around to it.
http://www.conservationtechnology.com
-- J.S.
>> I had heard somewhere that sillgasket does not have a long lifespan. <<
That's pertty interesting... Got any more info on that?
BTW - I think that another benefit a standard mud sill detail offers is that helps even out the often semi-uniform top of a foundation.
No, unfortunately, as I cannot remember where I heard it. THe sill gasket material that I have seen, is a pretty thick, rubbery material. I am not sure it would do much in the way of 'smooting out' the surface of the sill. But I have only seen one example of it, I must admit, and that was a long time ago.
Regards,
Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
The sill gasket material commonly available around here, which I use in slab on grade applications, I would say would be more in the category of cheap foam plastic. Never gave much thought to the longevity of the product, but pretty much assumed that most foam plastic is a 100+ year product as long as it is protected from constant UV light exposure. For example: http://www.dow.com/styrofoam/na/res-us/products/sill_seal.htm I remember back in the 70s, etc all the environmentalists were all up in arms because our dumps were being filled up with Styrofoam containers that supposedly would last 150 years. I'm far from a tree hugger but still refuse to buy disposable plates and cups made out of foam plastic.
I'm sure there are significantly better products available for significantly more money. For those projects that have budgets though, I guess that's what a builder does though... produce a quality structure while controlling costs.
BTW - is this super-insulated house gonna be in Tucson?
Thanks, Matt.
Actually, what I had in mind was a low-density foam, but was intending to use a foam dispenser, like a silicon sealer-type of dispenser. This came from the SIP supplier (or purchased locally), but I would bet the product you identified would produce nearly similar results. THe one that was mentioned in another response was more like a rubber gasket.
Actually, I guess I don't think of this design as super-insulated, but it is probably close. ICF for basement walls, and SIP's for the single, main floor, and roof. The super-insulated houses that I was watching back in the 80's still used the pink insulation, but usually with a frame of 2x6's and then a another of 2x3. Maybe the SIP is just a simpler way to accomplish the same. It certainly is easier to work with!
Regards,Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
hey, give the guy a break,
He asked a question, give him an answer. Simple, No need for long threads.
Concrete, sillgasket, 2x ---, fasten the trussjoists