Just over 4 years ago my son Todd and I were finishing a remodel of an old house that had to be retrofitted to meet ADA accessability standards so it could be used as a commercial building. Not a large job, but complicated.
It was several months into the job and money was getting tight (bet you never ran into that situation, huh?). The largest part of this job was adding a two story addition for a legal stairway up to the third floor and another down into the basement (three floors in the building).
The original plan was for an historically accurate staircase with fir treads, risers and landings. Now, I don’t get to build a lot of stuff like that so all through this job I was looking forward to that part (did I mention money was getting tight on this job?).
So the owner and I were going over the finish details and he gets real somber and says money’s getting tight and he’s decided to use carpeting on the landings and considering carpeting the stairs themselves. Dang it.
But, it’s their money, their building, I can certainly understand.
So I go home that night and wake up with the idea of using MDF for the stairs. 3/4″ for skirts and risers, 4/4″ for treads. Go ahead, laugh. When I mentioned it here at Breaktime several people scoffed and I can only imagine what some folks were thinking. But have you ever checked out the surface hardness of that stuff? Much harder than fir. So I priced it out, and talked to the building owner, explaining I’d never heard of anyone trying this, but the sheet materials for both stairwells would cost about $150.00 and Todd and I could machine everything and install it in a day. But he had to understand this was experimental, that we were relying on high quality paint to seal and toughen the treads, that if worse came to worse we could always come back in a few years and replace the treads if it didn’t work out. He went for it and those stairs went in slicker than I anticipated.
So anyway, Todd and I are just now finishing up a small remodel that includes a new set of stairs – to be painted – in an old house owned by a friend. Over the few months of the project I had it in the back of my mind to use MDF for the stair trim and maybe even the treads again. So I call the first building owner to ask how those treads held up, right? Number has been changed. Dang it.
So yesterday I invest a couple hours, drive up there to have a look myself. This building has been in use as a quilt shop for the past 4 years, in a cool little section of a waterfront city just South of Seattle. When I got there about noon the place was jumping. Must have been 20 shoppers in their pawing through bolts, chattering.
So I find the owners, exchange pleasantrys, and explain I’d like to scope out the stairs. They look great. Not so much as a dented edge or deep scratch from a rock in someone’s shoe. And these stairs get used FAR more than stairs in a house would. These people teach classes in the basement, their office is on the third floor. They are constantly running up and down these stairs with wet feet and all types of footwear.
I know. Four years is nothing in the life of a building. But looking at those stairs quelled my fears and on my way home I stopped at my sheet goods supplier to get the MDF we’ll be milling into treads and risers for this cool little stairwell we’re building…gonna try a few new details this time…really looking forward to the design challenges.
Replies
While I'm an advocate of MDF, I'd have to say that at first blush I'd be wary of the milled nosing of the tread holding up on a stairway.
Residential indoor, with socks? Sure. But commercial use, with shoes/boots tracking grit in from outside?
I have to say I'm suprised. Then again, as you wrote, using a good quality primer/paint would do wonders to protect the nosing.
Bravo!
I'm loving everything about MDF but the dust. I did a similar low-budget project a few years ago in my own house. A "U" shaped bookcase to wrap the stairwell opening, faux beams on the cathedral ceiling to hide wiring and break up the ceiling plane, and about 130' of wainscotting on the kneewalls (with 10 doors for behind kneewall storage access) in an attic project. Also built in "window seats" on the full length (about 18') of each gable end wall to hde the AC ducting and added flip-up seat tops for storage below. High quality in design, but all MDF (and low cost) in execution.
Looks fabulous.
Same thing about the dust, but here are two other low-budget uses where MDF has excelled:
1...partition walls for a closet with bare bones 2X2 framing and whole sheets of MDF stood up long way...coat of primer and top coat to match other walls.
2...long permanent work bench surface for SLCMS. 4X4 legs left over from deck, 2X4 frames, MDF glued and screwed down, holes plugged, two coats of varnish, oak long fence secured on top.
MDF is harder than many wood species.....I'm looking at the MDF standard and some test results right now.....the test they used shows MDF at a J.Ball hardness rating of 1180 pounds.....solid oak rates 1200-1400 lbs. With poly on 2 sides, MDF goes to 1250 lbs. Fir plywood is only 655 lbs, and I don't have any numbers for solid wood softwood species.
Now, this doesn't compare the hardness of the edge and the flat part of the sheet, but it's pretty hard. I know I see more and more jobs specced with raw MDF and a stain and clear coat.....cabinets, doors, counters....it holds up pretty well. I'm not surprised about the stair parts. But if it does prove that the MDF isn't quite hard enough, there is always HDF....don't have any numbers at hand, but still very affordable.cabinetmaker/college woodworking instructor. Cape Breton, N.S
Jim,
I'm impressed.I've seen MDF used as flooring commercially. It failed, but only when heavy ride- on waxing machines were on it.
I think the only problem would be the milled or bullnose edge, because once profiled, that exposes the softer core of mdf to damage.But on the whole it's a tough, dense product. So much so that the CIA was considering dropping giant hacks of it on Saddam's palaces.hahahahaha.
best of luck.
you can but stairs with MDF risers & treads here in the UK
Yeah man, I was worried about those edges. In my mind's eye I saw them beat to crap...crumbled maybe. Maybe horizontal fissures as the MDF kind of delaminated. But they looked great. I was amazed. That's why I figured it was worth reporting back to the gang about them.
I'm sure glad Mongo has testified so often about the oil based primer over the years. I think that's what makes all the difference on those edges. And Adrian and Joe Fuscoe are the ones who got me really playing with MDF in the first place. Thanks all you guys, that's some great stuff.
I use MDF mostly for things like fireplace surround and mantels that will be painted - - great stuff !! But I've also 'heard' of an exterior grade MDF. If there is such an animal, it sounds like it might be better for wet feet and such. (I actually heard of it in an old issue of FHB about some front porch posts 'wrap').
Maybe thinking of MDO
Medium density overlay?
Might also be called sign board
I think the ext. MDF is marketed under the name "Medex".
Jon Blakemore
I'll try to find that old edition in the next day or two and get back to you.
The exterior grade is called MEDEX. sheets are something like 50" x 100"
GP Primetrim is vary similar stuff and preprimed on one side.
Comes 7/16" x 11-1/4" x 16'
or 15/16" x 11-1/4 x 16'
This recent issue of FHB has an article on composite trims exterior by Gary Katz
The MDO CAG mentioned is a fir exterior grade plywood that has one or two sides sanded and finished with a paper surface like a thin laminate. it doies have the nickname signboard, because it sees use that way
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Good info, Piffin, thanks!
Sorry Piff, MDX is the same as MDF, except it has no formaldehyde.
I work with it most every day,it's not an exterior rated product.
I use it outside, and it doesn't fail. MDF does.
They sell it to me as an exterior product under the brand name MEDEX. Mqybe we aren't talking about the same product.
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Since I have never been steered wrong by my lumber guys, I dug a little deeper to find what is behind your statement, since it differs from what they tell me and my own experience. I ran a couple searches on Google under exterior + medex and medex + mdf
I found that Medex was first developed for highway signs.
Hmmm, we don't have many signs here on the island, but the last one I saw was outside.
True, the maunfacturer's website and spec sheet says that medex is not recommended for exterior trims, soffit, or siding, but then they provide specs for how to prep and paint it when used outside.
Most of all the hundreds of retailers refer to medex as Medex Exterior grade.
Then there are the city and archy sites that spec the prouct for exterior use.
Confusing isn't it, when the manufacturer says don't use it outside, but if youdo, here is how to paint it, and then they provide it to retailers who almost unanimously push it as an exterior product?
"MEDEX MDF—THE EXTERIOR MDF
1/2" 49"x97" Medex (exterior MDF)
5/8" 49"x97" Medex (exterior MDF)
3/4" 49"x97" Medex (exterior MDF)"
from -
http://www.schallerhardwood.com/new_page_2.htm
"Sierra Pine Ltd., Medite Division
P.O. Box 4040
Medford, OR 97501
541-773-2522
Medex and Medite II formaldehyde-free, medium-density fiberboard
Local supplier:
Fine Lumber and Plywood
9407 Brown Ln.
Austin, TX 78754
512-836-8990
http://www.finelumber.citysearch.com
Made from pre-consumer wood waste and using formaldehyde-free resins in their binder. Applications: Medex is used for exterior applications while Medite II is used for interior applications. For interiors it is commonly used in cabinetry and molding. The panels generally come in 1/4", 1/2", 3/4" thick and 4'x8' sheets, but larger sizes are available up to 5'x18'."
from -
http://www.ci.austin.tx.us/greenbuilder/srcbk_6.htm
and
"MEDEX â, designed for Exterior use, is also manufactured by the MEDITE division of SierraPine Ltd. This unique panel is engineered to provide minimum formaldehyde emissions, below ambient rural outdoor levels. It is suited for use where there is concern over these emissions which are common to most wood panel products. It is recommended for use in schools, museums, day care centers, medical facilities etc. MEDEX has been shown to have formaldehyde emissions below the ambient outdoor levels found in much of the rural U.S.
MEDEX is also suited for use in interior applications where moisture is a concern. It is a good replacement for plywood and solid wood in non-structural applications such as countertops, window sills, bathroom cabinets and woodwork, raised panel inserts, etc. See our stock list for availability."
from -
http://www.phillipsplywood.com/fiberboard.htm
If you read the data sheets in the PDFs that Sierra Pine puts out, you will see some other differences in the products. For one - Medex is slightly harder on surface and softer in the middle on the thicker sheets.
Also. they show that swelling is 2-5% after total immersion in water for 24 hours. since I paint my product, and don't immerse my houses, that sound acceptable to me.
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Some conflicting specs on this product, for sure. I find medex(MDX) a little denser than mdf and less likely to become fuzzy on an exposed edge.
For exterior use, it's probably okay as long as the edge is well-sealed. Better products exist for exterior use, IMO.
Edited 7/20/2004 2:35 pm ET by JACKPLANE
Jack,
Here is how I reconcile the confliting info in my reasoning...
There are hundreds of us who do succesfully use medex outside when it is propperly painted, and it was probably first developed for that application, but in the intervening years. the manufacturer has learned that it does not do as well as it was first intended and wants to avoid liability claims so they withdrew the exterior rating at some point in history and avoid excessive claims as to its application and marketability for that use. That is understandable after the lawsuits against Masonite and other hardboard siding.
But meanwhile, retailers were slow to change the marketing, especially since so many of us used it. I've lost track of how many curved and round exterior window casings I have milled out of it.
It is one of the early types of man-made substitues for wood in exterior products and has been or is being suplanted by a second generation of products such as Azek which is also sold in sheets and can be milled on the job.
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The bottom rails of foam-filled exterior doors need to be as rot-proof as possible.
In 1988, ThermaTru, a large manufacturer of insulated residential steel and fiberglass doors, used redwood for the bottom rails in all of its doors. Its source for the redwood rails dried up and ThermaTru switched to incense cedar, the cedar species used for the world's supply of pencils. Pricing for that source became volatile, and ThermaTru sought a material that would be in long-term supply, preferably a composite of some sort.
Medex was tried and rejected after testing. Water uptake was severe, swelling occurred, and door bottom ends deformed.
ThermaTru now uses a composite rail material made from ground wood materials, recycled plastics, and special binders.
Hi,
I wouldn't expect it to hold up for door bottms, since you could not paint up in the rail channels/slots where the other bottom hardware locks in place
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FHB #132, page 106. I've done some work for this top-notch firm, but wasn't on 'this' job.
Edited 7/18/2004 4:25 pm ET by TR
We had some porch spindle done in MDO on a 1880's restoration. 5 years and they sill look great. We had a friend with computerized routing table take the original fir Queen Ann style spindle and strech the design on his computer to meet the UBC code height reqirments. and he routed out 8 foot sheets that we atached to the orignal posts. It looks great and holds up the the worst of the sun snow, and rain.
Jason
My regular yard is stocking an exterior MDF called Extera. Its about $68 per sheet.
Around here it's called Miratex, and it seems like the real deal. Don't worry, we can fix that later!
In my regular yard, Miratec(x) comes in dimensional sizes ( 1x, 5/4,) up to 12" wide.
The Extera is a sheet product and is ( I think ) 4'x8'
Maybe your yard carries a little different product line?
BTW, I'm pricing a custom front entry which will be mostly Miratec and Extera. I plan on using the Extera for some raised panels.
Shep, whereabouts you located? I'm in Bordentown, just south of Trenton.
I live in South Plainfield, right on the borders of Somerset, Middlesex, and Union Counties.
The yard I'm talking about is Huston Lumber. Only the Oldwick branch has the Extera, tho.
Jim-
What was the front edge profile on the treads? And then I suppose you sealed the whole thing with oil based primer?
MERC
If you dig a little bit you can probably find HDF... high density fiberboard. The core of the panel is made of finer dust than MDF and might make a nicer bullnose. Some cabinet door manufacturers use HDF for their raised panels because the exposed core in the panel detail paints out better.
I think we used a 3/8" roundover bit top and bottom of the front edge, Merc, and let it hang 1/2" past the face of the risers.
This set we just finished installing today we used a larger roundover, might have been 1/2". I'm not sure exactly how you call those bits out, but this time there's no flat spot on the front or exposed end of a 4/4 tread, just a nice continuous bullnose. Came out great.
Yeah, we (actually the painter) prime them with oil base on Mongo's advice years ago.
David - I've never tried HDF. Have to look into it. Bet that stuff is HEAVY. That frikkin' MDF is enough to encourage you to develop some sound handling techniques. Can't imagine what HDF must weigh. Last week I picked some up from Architectural Woods, in Tacoma, and asked about a high density MDF - the guy looked at me like I was a Martian.
Almost comical to come across a sheet of ultralight in the scrap storage area, grab it like standard weight and realize it's so much lighter.