Hide the Timber Frame?!

I've got a client who loves the idea of a timber frame for her new 30' x 44' colonial house. She also wants true lathe and plaster walls, no sheet goods that will off-gas, but worst of all, doesn't want to see the frame anywhere except the cellar . I'm left considering how to hide all our work while giving her the house she wants at a reasonable cost.

Would an in-fill system of using dimension lumber to hold exterior sheathing as well as interior lathe hold up economically as well as resist plaster cracking sufficiently? How about building the frame and letting it dry in place for a winter before putting plaster on? Has anyone had to hide their work before?

I'm afraid in the end that she may not go with a timber frame when she realizes the extra costs involved with adding dimensional lumber...? Any advice greatly appreciated.

Cool, a great example of a modern building problem. Sounds like she wants it the old way - so why don't you supply her with "the old way"? Frame is purely functional, spend NO time on finishing details, your challenge is to supply a fast, but stout frame. That is a fun exercise if you are used to the typical polished timber furniture usually produced. We figure about 50% of our time is spent on "finishing", that time should be saved in this case - go fast!
Incorporate vertical nailers every 1-2' for to attach lathe strips. Most of these buildings also had very few knee braces to work around, but she'll need enough to meet code.
You know how screwy dimension lumber is now, that will bring about its own problems.
Are you thinking about it too much? Let her decide if it costs too much, she may choose to trade off something else and keep your framing if budget rises, especially if you're working well with her and present accurate information for her decision making. You have a unique chance to recreate some traditional building elements, go for it. Sell her on the value of that. Good luck.

Randy's idea of looking at how the old-timers did it is a good one, I think. For example, I'm finishing up restoration of an 1820 Greek Revival farmhouse that is exactly as you describe - timberframed, but visible only in the basement and attic.

In this case, the posts were 6x10, and the side walls are 6" thick and the gable-end walls 4". (Of course the insulation of choice at the time was brick, or nothing). Side wall studs were added between the posts to hold siding and lathe. Some were tenoned top and bottom, some just nailed in place. Many side wall studs were on the flat, and doubled with a gap between (i.e. separate studs for exterior siding and interior lathe). This has the advantage in modern days as allowing a little insulation between and creating a thermal break. Some studs are required for window framing. They were quite liberal in just nailing scraps wherever needed to create a landing for lathe.

Overhead, second floor and attic joists are sawn 4x8's spaced close enough to nail the lathe to, no additional nailers needed.

If it were me, I'd just use rough-cut studs from the same supplier my timbers come from.

Hope this makes sense - happy to clarify if I can.

Cheers,
Dan

As I read Dan & Randy's posts I'm remembering a TF horror story I heard years ago, where a 5 year old frame, exposed inside, with stick frame infill, had to be torn down. Moisture laden air found it's way through cracks at the stud wall/post intersections & condensed on the inside of of the exterior wall & rotted things badly enough to cause the demise of the frame. Of course, the original houses were more air/vapor permeable ( i.e. they leaked) so this wasn't a problem. I think good detailing, proper venting & wise choices of vapor barriers & their placement should keep this from being a problem with your project. Good luck.

Scott, you're right, that is a horror story. I wonder if a complete interior plaster job provides enough of a moisture barrier to keep warm, moist air in?

Randy, of course I'm thinking about this too much. I was tongue-tied when she suggested covering my frame, but I've since adjusted my attitude and see your point of selling it on it's own merits. You also mention code - we really don't have code in rural Vermont, as you know. What is your understanding of the required frequency of braces?

I'm still left with the question, however, of frame drying and plaster cracking. This seems to be the most risky part of this design. I'm thinking of using kiln dried 2x8 studs for infill, but wondering if lathe could be applied to the 7x10 posts (7.5" stud clears the 7" depth of post)with a buffered mounting system, so that as the frame dries down, it doesn't have to pull away from lathe and plaster. Has anyone tried something like this?

Dan, I'm familiar with your description of the house you're working on. My own house is an 1830 cape with a dutch frame, posts are 5x8 with bents spaced every 3-4'. There is some wisdom among the methods of old, but the challenge is providing quite a bit more modern convenience (insulation better than brick)while paying homage to the past.

How much do you think a pine frame would dry down in one winter heating season?

Thank you all for responses.

Uff, lots to think about huh? You can't exactly take 200 year old methods and assume they'll make an adequate contemporary house. I think you're on the right track to think thru the details. Before you go too far though, get the client signed up. Encourage her ideas and admit that it is a challenging endeavor - that you'd like to take on. Sign her up for a Design Phase where you'll get compensated for some time spent figuring it out. It gives you both an "out" if it gets to unweildy. Then go to work - several viable solutions will emerge. A good building motto is "It is always possible, may be expensive, but there is always a way." Money invested in design will be saved later.

Suspect you'll end up with overlapping layers and well thought out movement (buffer) zones. Lateral bracing needs to be figured out for that particular job. Can be interior shear walls, vert/horz grids of nailers, sheathing layers, maybe no knee braces at all. Need more info.

Can someone explain what a infill system entails...is this an alternative to sips??

jroy,
As the name implies 'infill' is whatever material you use to occupy the spaces in the walls between the posts and girts or other horizontal members. In the olden days (still practiced some today in replications) this material could be daubing (a mixture of clay and straw with or without woven small sticks for lath) or brick carefully fitted into the spaces.
If you use dimensional lumber, batt or sprayed insulation and wallboard you 'infill' with these modern materials. All theses methods are in lieu of SIPs or other externally applied 'walls'.
There are many books on the subject.
deralte

Emmitt..if you "infill" does one run the risk of having seperation at the timber/infill material junction as the timbers move and shrink..can you do an "outfill" using the same techniques but putting them on the outside of the timbers so not to be effected by movement & shrinkage??

and, if you could point out the books that reference infill systems I would appreciate your guidance on this..

Randy, thanks for the advice. We'll see if she bites, and if so I'll be back looking for more insight. Cheers.

Jroy
What you are calling outfill describes the normal practice of hanging SIP's on the outside face of your frame.
Do a google search on waddle and daub.
Contact the folks at TTRAG, better yet go to their meeting in MA this spring
Visit the library at the Heartwood School
Did you try an "infill" search here on the tfg website ?
good luck

Robert Laporte does a sort of an "outfill" using a sort of Larsen truss applied vertically to the TF & filled with a somewhat compacted clay/straw mix. If you google "econest" you'll probably come up with their website.

I just want to double-ditto Scott's concerns. (At least in cold regions.)

I saw a frame need major repairs within 10 years, due to condensed vapor on the outside faces of the posts. I blame insufficient vapor retarder detailing, combined with modern insulation.

Foe me, this is a concern with an infill system, since every post represents a penetration of the vapor retarding plane and the conditioned space within the wall. As we know, SIPs need perfect edge-to edge sealing, for the same reason.

I'd think in this case I'd run both strapping/lathe and (taped) vapor barrier continuous right past the inside faces of the posts, since they are concealed anyway. Thus to reduce plaster cracking, also.

Good luck.

Pete

this is just a thought..but would it be possible to build a 2x frame 24"oc on the outside of the timber frame, with horizontal strapping on the inside face, after wiring is run have it insulated with spray foam(which will incapsulate the studs reducing conduction)..i know sips basically do the same thing, but the costs of me putting the walls together is cost effective from my point of view...

jroy,
the box in a box approach will work if you have enuff foundation on which to sit the outer 2x frame. If you want some real insulating go with 2x6's. with a tf complete interior now only holding up itself sounds kinda like a tad bit of overkill.

i agree that it sounds alittle overkill, but i am not totally sold on sips...i am not a fan of osb, and theyre expensive to boot. seeing that i am not hampered by time constraints, i dont mind building the "skin" out of 2x material.

what i would like to know is if you guys think this is workable, and if i am re-inventing the wheel so to speak...

on another note, the knowledge that i have gotten from this web site has been invaluable to my understanding of tf'ing..many many thanks to all

It is workable and has been done many times. It is also redundant structurally and not as energy efficient since wood is not that great an insulator. It is also mucn more difficult to limit infiltration and therefore you get hit again on energy efficiency. Would you use plywood as an alternative to the OSB? What about on the floor? Some have found OSB stands up better to the weather while you raise your frame and get a roof on it. I wonder if your deck would be subjugated to the weather even longer if you were to add a stick frame around your timber frame? Some people don't like OSB for fear of the release of toxins into the home, but a curtainwall panel would release these (if any) to the outside of the home. Just playing devil's advocate, but I am a proponent of energy efficiency... in a perfect world we would have a green, affordable panel available to us!

Murus (are they still around?) made a green panel, I think it was basically modular stick walls with cellulose blown in. I can also attest to the potential disaster of infill systems. With enough maintenance and foaming in of joints between sticks and posts it can work, but is it worth it? Will it be worth it when oil is $3/gal or $4?? I think the industry has settled on panels as the lesser of evils and we're all hoping for greener enclosures.

Paul
what if one uses spray in place foam (icyenne system)in lieu of celluose??..by using horizontal strapping on the inside the foam would incapsulate the studs limiting the amount of conduction...and by doing so filling the wall cavity completely..i am planning to use either plywood or pine boards cut on site for sheathing

jroy,
I've recently been working on enclosuring a TF with 2x8's, on the inside we used a wind stopping textile, on the outside gyproc ( to create a shear diaphragm). This being in Sweden and here we don't have a SIP industry to speak of, this way was most economic ond gives good insulation values. As insulation we used cellulose that was injected under pressure through holes made in the textile. The cellulose was recycled newspapers from Englad! added with Bor, for fire safety reasons. On a trip in Vermont,USA, I saw a similar system but they had used recycled JEANS, and instead of textile they had used a plastic moisture barrier. The textile in our project was choosed to get a house not to airtight, with an airtight enclosure you need to keep a sharp eye on ventilation system. Of course, here we never install AC systems to keep cool during summer, so the problem with air tightness and ventilation might not be the same as for you. All I can say is I like the newspaper way and that it seems overkill (structurally) to build a 2x wall outsida a TF, but what to do: it's cheap and a nice system when it comes to installing wireing and windows.

Can you tell us more about the wind stopping textile?

The textile,
it comes in different widths and lengts, and we have a couple of different brands.
In our case it's a nonwowen-textile and consists of 2 layers of polypropen laminated with polyeten. The lamination lets water vapor move through the textile , it's light 72 g/square meter and is kind if elastic - very easy to work with ( just cut an x a bit smaller in size than that vent hole and press the textile over it and use some tape to fix it), it's very difficult to tear - a very sharp knife is required. And it effectively stops the wind. Usually placed just utside of the insulation.
NB: code in Sweden talks about a vapor barrier on inside of insulation, but it's not enforced/requiered.