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I need help!!
I have been constructing a pole house for the last several years and am now (finally) nearing completion. I am building a walnut and oak spiral stair. The treads are 1.5″ thick walnut and measure 4 inches on the narrow end and 18 inches on the wide end. They are laminated from 1″x 6″ walnut boards face glued and then edge glued to form the blanks from which I constructed the treads. There is a .5″x .75″ spline used between the face glued boards used for alignement and strength. I used West Sytem epoxy for the glue. The treads are supported on Red Oak knees that are straped to a structural wooden pole (see picture). All materials were kiln dry and stored on site for the past several years in a garage and then in my shop. I have not yet put a finish on them yet but plan on using polyurethane when I am complete with the Stair assembly (soon). To say the least this is the most complex and tedious project that I have undertaken. I have 5 months of time into the project (and lots of $$). The stair was turning out beautifully and now disaster has struct.
All the treads have begun to split and crack. Mostly down the glue lines but some splits are in the field. Even the face glue has begun to fail. I am not entirely sure of the cause so I am not sure as to a possible or practical fix. Has the inevitable flexing of the stair caused the failure (my first guess)? The knee and balusters are probably causing the steps to bend slightly because they work against each other when the stairs flex under weight and most cracks begin at the unsupported end of the tread. Has the lack of a finish caused the failure? We have experienced a few hot and dry days in the last month which may have caused shrinkage stresses and the failures I’m seeing. I live on the north coast of California and our summers are usually cool and fogy and the fall is warm and dry. But we do not experience the extreme humidity changes as you do in the midwesst or east.
As of yet the treads have not structurally failed. But the rate of deterioration that I’m observing indicates that structural failure is possible in the near future. I can add either steel or wood stiffeners to the outer end of the tread to decrease or eliminate flexing and bending. I can seal the wood to slow down the expansion and contraction and subsequent stresses. I can repair and fill the vertical cracks with epoxy. I can do a lot of stuff to fix the problem. I can even do it all. But Time is progressing. Is my design flawed? My worst case senario is to remove each step and replace the tread with 1 1/8″ plywood venered with 1/4″ walnut. This will be a lot of work but if it needs to be done, well what choice do I have? Would I still need a wood/steel stiffener on the unsupported end?
I need any ideas that may help solve my problem.
Replies
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Hi Dean Wolfe.
Nice job. Good design. I like it.
Of course, I cannot say anything here which is for sure, because I cant see it close.
However, from what I can see, I have some concerns.
If I understand correctly, you laminated two 3/4" walnut boards to make 1 1/2" thickness. Further, that you edge-joined to achieve your maximum 18" tread width.
I am concerned about the West System epoxy glue that you said you used. I might have just used yellow glue. I get the feeling that the epoxy is restricting movement in the wood, and the wood is responding to the restrictions.
Further, I dont know walnut to be a structural wood. I think that a tread is required to carry 300lbs per square foot load. I dont know that walnut carries that.
When someone bounces down a stair, the weight is directed to the nose. When someone runs up the stair, the weight is directed to the nose. If your tread nosing is not strong enough to transfer this weight to the pole, then the wood is going to fail.
I get the feeling that your design might welcome the introduction of 1/4" steel to carry the tread load. I think you can rout out the bottom of the tread in a way that the plates is covered by wood at four sides. I would stay with the walnut you have. And I think you might have to use steel to transfer the load from the tread plates to the pole. That would be sandwiched by your oak pieces.
I would stay away from plywood. I dont think it would feel right.
Let me know if my suggestions prove worthy, or if I might be of further assistance.
Hope this helps.
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alan:
The stair has not seen any real use yet, so structural failure because of wood type does not seem likely. I used West System epoxy because of its working time.Some of the hardeners give you up to 2 hours pot life depending on temp. It is used extensively in boat construction and normally takes alot of abuse. However, I am calling the manufacturer tomorrow to explore potential application and use problems. We have had a few hot days recently and have heard stair creeking with no load, so mabie wood movement constricted by the structure is the culpit. I am considering adding a steel stiffener at the unsupported end of the tread to constrict flexing. Another posibility is that the Oak knees are flexing the stair upward. Jumping on the knees alone only yeilded a max of 1/16 flex at the outer end. I may of over tightened the strapping and raised the end thus induced upward flex to the stair tread. Embedding steel is a straightforward fix that I am already considering. Question ... if the cracking is induced by drying because of the last few warm days, would filling the cracks cause more problems when the wood returns to normal moisture content?
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Dean,
I have to agree with Alan.....
I think the glue may have failed you. Here in Texas where the humidity rules, nothing is safe. The fact that you had to glue up so many pieces to make the treads was just asking for trouble.
Try some good old Elmers yellow or white glue next time. Even Titebond if you have to.
I think the introduction of steel will help the problem. Replacing the built up treads with solid stock walnut would be better......but that's expensive.
You might try re-gluing the treads and then bolting the pieces together and pluging the holes with walnut plugs. If you keep the plugs geometricly even on each tread, it might look good. Maybe add a diferent wood like maybe bloodwood for the plugs for contrast.
Just an idea,
Ed. Williams
*I'm no woodworker, so this is a question not a suggestion:Did you interleave the layers of 1x6? That is, does the top 1x6 span two lower 1x6's and so on? Or did you just glue 1x's together to make 2x's, then edge-glue, and if so, how did you make the bond strong enough?It sounds pretty clear that the wood wants to move and can't, so it's cracking or breaking the glue bonds. It's not the temp. so much as the humidity that causes movement -- has that changed recently? West epoxy is strong -- AND you used splines -- so the wood will break too. If one board moves and another bound under it can't or has different ideas, problems. This may be aggravated by the pie-wedge shape of the treads, causing greater movement at the outside than inside of the radius. You might be able to break the treads apart at the glue lines to salvage as much as you can.Sorry this happened to you. Bummer.
*Dean,I cant add much except that west epoxy is strong and flexible. Did the glue joint break the wood or the epoxy. If the epoxy broke there could be one of two problems. Bad mixing, If you used pumps did you get the right pump for the type of hardener you used. Also these pumps fail fairly often. did you use your calibration vial before starting. Also some woods which have very tight grains and a lot of oils in them can be diffucult to get a bond with. Oak works well teak and Ipe do not. I have neber used Walntu with the WEST system. The tight grain would lead me to believe that that could be a problem. You might try e-mailing Sam Devlin at Devlin Boatbuilding .com. He could probably tell you.Rick Tuk
*Dean,Sorry to hear about your problem.Do you have any "cross-grain" construction in the stair--that is, a piece attached perpendicularly to the grain on another board? For example, are your two layers of 1x oriented the same way with the grain parallel, or is one layer going one way and the other crosswise like plywood veneers? Or is there a cap on the outside end of the tread whose grain is perpendicular to the tread?These conditions can cause wood shrinkage to result in cracks when the board is held to its original size and the wood itself gets smaller.I have used West System and can't imagine that it is the root of the problem, but who knows.Good luck,DougPS--I couldn't get your picture to download.
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Joseph Fusco View Image
*Joe, strangely, that's one of the few pictures I havn't had trouble with. I usually get a blank screen when I click on a picture, or a script error message, then when click the X in the top right corner later to exit, the picture loads. Anyone else have that problem? Chuck
*This is a small sample of what I get downloading Dean's picture:>ÝNiy!zàcàbO–pIÈÈ¥.àd/×$š‰Û&gWá;±emÁòWÐS[O³òõî?çü*Ñ`¨Y±É#°ÿ˜ÝTÏõúöt¬¼ý;vW€‚âÙ“þY>yúsYwtlÃ9Ó|¹ãÖ¥ÅMó¸U+"ŸcÓ¿ÿ•¦™q¨ÑäáÛlò3Ú¦ÙϨÏqŠŠSurely a word has been coined to describe the above kind of nonsense characters, but I don't think I have ever heard it.Rich Beckman
*Rich,That's what I got.Ed. Williams
*Not sure whether the problem lies in the photo's tags or Netscape ... but I got the same thing. I just resolved the problem, and wish i could attribute it to brilliance, but I used what programmers call the "brute force" method.I shrank it a bit to comply with the 50k barrier. Very nice-looking stair!... now, about the apparent Code violations ... :)
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Joseph Fusco View Image
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An update for those who have contributed to this string.. First the pic is in JPEG. All who have a browser should be able to view it. Second, the pic is of the stair uncompleted. When completed it will meet the baluster requirements and rise and run, and headroom clearance as required by the uniform building code for spiral stairs. In fact the local building department required that I add an additional step, more than the UBC required. Third, good news I have a solution to my problem in hand and will begin implementing it in the next few days. Apparent problem is moisture and the stair being unfinished yet. We have had some wild swings in Hunidity in the part of CA in which I live in the last few weeks (unusual). Cracking resulted. My slow building process being to blame! I should have sealed the steps sooner. Second, a contributing cause is that apparently all epoxies (and glues for that matter), while great at cyclic loads and flexable and strong have problems with continuious loadings and should be reinforced. Solution, will be adding a buried steel stiffener to take up the load from the joints. Thanks to all.
Dean
*Andrew: the photo is a pic in JPEG, your browser should open it. Yes, it was above the 50k limit. Sorry. Second the photo is of the stair uncompleted. When complete it will meet all requirements of the UBC, rise, railing hight, baluster spacing and head room clearance for spiral stairs. It will be even more conservative than the UBC requirement for rise because of a local Building department requirement. By the way this is my first exploration into a chat room type environment and am surprised that you thought it appropriate and polite to add the ZING at the end of your message regarding the code when you do not have all the facts and my question and request had nothing to do with the code.
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Dean,
I am glad you found your problem.
About andrews "zing" dont take it personal. Please note he also complimented the stairs. If you post something like that you are bound to get answers that are not part of the question. Notes like that could save you a lot of time and money, at worse you could answer that they are code compliant. This is a very civil post until someone takes something personal. If you will take some free advise (worth every cent) If you dont like it let it pass. I feel it just isnt worth my time to get aggrivated over it.
I liked your stairs, by the way. Hope to se some more Pics of your house soon.
Rick Tuk
*Geez, I was being facetious! The obnoxious smiley :) thing is meant to defuse an apparently abusive comment. Also, I wouldn't want to kick you while you're down.Interesting about the epoxy. As for the image, the problem was likely that you sent it as an "enclosure" which is not an entirely generic method. NS couldn't figure out the format and defaulted to text "garbage" -- I got it too. A .jpg suffix usually works to tip off the browser, as does sending the image to Taunton as an attachment or posting it on the Web somewhere and including an reference (HTML or not) to its location in your message. Someday it won't matter what computer or software you have, but not yet.
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Andrew:
Sorry I was so sensitive. I will be less so in the future.
Dean
*Would folks be interested in seeing more pics of my project? Just for info, I am an owner builder and have been building my house part time and full time for ... let me count ...7 years or so. It is a pole structure & and basically poll ands beam construction, no foundation, no load bearing walls etc. Pole go 16 ' into ground. The structure is 8 sided two story and has more angles than ........ I am nearing completion and am finishing the interior in Oak, Maple and Walnut with a little souther yellow pine mixed in. I hope to publish an artical or two when I am completed. My wife and I have done all, I repeat, all the work ourselves including raising 150 structural beams. Only help to date is withe the septic, drilling 16 foot peir holes and some crane work for the poles and 4 of the beams. If folks are interested I will start a new subject or is there a more appropriate format. Mabie I should open a personal web page. Any Ideas??Dean
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Dean,
Joseph Fusco
View Image
"The price of apathy towards public affairs is to be ruled by evil men." -- Plato
*I would like to see pictures.Also, is the problem with the stairs...no crossbanding?Thanks.
*Dean,I hope you're resolving your nightmare by now. There's so much to think about when building a difficult project and wood movement is an important consideration that often gets less attention than it deserves.My understanding of your glue-up is that you started with 1 1/2-in-thick walnut and edge joined it with 1/2-in-thick by 3/4-in-wide splines with epoxy in the joint. I don't think, as suggested by others, that you made up the thickness with two layers of 3/4-in-thick material. If I'm correct, I don't think your glue choice is the issue here. I used the Gougeon Brosthers' glue for about fifteen years, when building boats, and still use it in my woodworking business when I, like you, want long setup times (or when the object is going outdoors).I think your problem relates to how the treads are supported front to back and where you fastened the treads. What, besides the laminated piece thats banded to the center pole supports the tread? Did you add a front-to-back frame to the tread? I believe you must have, or the tread would split over its support. And if you did, how did you fasten the widest part of the tread? Is it fastened at both the front and back edge? If so, when the piece comes-and-goes, it has to do it in the middle, between fasteners - and your tread then splits. Instead, if you fasten only the nose, which should stay in position, you've got to let the back edge move. An 18-in-wide piece of walnut might expand and contract as much as 1/8 to 3/16 inch - probably the total width of cracks in any one tread. If you fastened your treads as I think you did, I suggest you remove the fastener at the back edge. You might replace it with a tab of steel top and bottom, in which the tread can move about, but which contains the tread from up and down movement.If you leave both fasteners in, I would not fill cracks with epoxy, because when the tread swells, it'll bear against your fastenings and you'll have a different repair to make. If you can release the tension of front and back fastenings, and fix the treads as I suggest, you might be able to then epoxy the splits and clamp the tread. But do this only if only one (the front) edge is anchored.
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I need help!!
I have been constructing a pole house for the last several years and am now (finally) nearing completion. I am building a walnut and oak spiral stair. The treads are 1.5" thick walnut and measure 4 inches on the narrow end and 18 inches on the wide end. They are laminated from 1"x 6" walnut boards face glued and then edge glued to form the blanks from which I constructed the treads. There is a .5"x .75" spline used between the face glued boards used for alignement and strength. I used West Sytem epoxy for the glue. The treads are supported on Red Oak knees that are straped to a structural wooden pole (see picture). All materials were kiln dry and stored on site for the past several years in a garage and then in my shop. I have not yet put a finish on them yet but plan on using polyurethane when I am complete with the Stair assembly (soon). To say the least this is the most complex and tedious project that I have undertaken. I have 5 months of time into the project (and lots of $$). The stair was turning out beautifully and now disaster has struct.
All the treads have begun to split and crack. Mostly down the glue lines but some splits are in the field. Even the face glue has begun to fail. I am not entirely sure of the cause so I am not sure as to a possible or practical fix. Has the inevitable flexing of the stair caused the failure (my first guess)? The knee and balusters are probably causing the steps to bend slightly because they work against each other when the stairs flex under weight and most cracks begin at the unsupported end of the tread. Has the lack of a finish caused the failure? We have experienced a few hot and dry days in the last month which may have caused shrinkage stresses and the failures I'm seeing. I live on the north coast of California and our summers are usually cool and fogy and the fall is warm and dry. But we do not experience the extreme humidity changes as you do in the midwesst or east.
As of yet the treads have not structurally failed. But the rate of deterioration that I'm observing indicates that structural failure is possible in the near future. I can add either steel or wood stiffeners to the outer end of the tread to decrease or eliminate flexing and bending. I can seal the wood to slow down the expansion and contraction and subsequent stresses. I can repair and fill the vertical cracks with epoxy. I can do a lot of stuff to fix the problem. I can even do it all. But Time is progressing. Is my design flawed? My worst case senario is to remove each step and replace the tread with 1 1/8" plywood venered with 1/4" walnut. This will be a lot of work but if it needs to be done, well what choice do I have? Would I still need a wood/steel stiffener on the unsupported end?
I need any ideas that may help solve my problem.