Shangri La

Shangri La

Monday, June 22, 2009

Framing the Floor

As the LSW reported, we made significant progress last week. We began work at noon on Saturday, and – despite rain and drizzle Sunday morning - managed to get 90% of the floor done by Sunday at 3. I drove back up by myself on Wednesday to finish the job.

My notes from this effort:

The wood was delivered wrapped in metal strapping. I figured there must be some way to remove it without a metal cutter (one of the few things I didn't bring), but I’ll be damned if I could figure it out. In the end we had to shimmy the first piece in each bundle out to loosen the tension and get the rest free. Next time, I’ll bring metal snips.

The top of the foundation looked more level than it actually was. The sills bolted down tight, but after the floor and face joists were in place, I was left with 1/8" to 1/4" gaps in the northeast and northwest corners. I began to shim them, but decided to wait until the walls and roof were up to see if the weight of the whole structure closed them.

I didn’t think to check how the metal bridging – which is sold flat – actually gets installed. My intention had been to install two rows, each about 5’ in from the face joists. I ended up bending the first row into a ‘z’ shape and nailing them to the inside faces of each joist. Something about this didn’t seem right to me, but I went from one end of the building to the other anyway. When I got home and looked it up, I saw that each end should be nailed to the top and bottom of adjacent joists, and felt like an idiot. After installing a row correctly on Wednesday, I considered ripping out first row, but decided to leave them in place so that the next owner can wonder what the hell I was thinking.

My new Paslode cordless pneumatic nailer performed flawlessly; it’s going to be worth its weight in gold.

On Wednesday, CVPS was on site swapping out the pole that is going to feed power to the house. I spent some time talking with the crew, and learned that the Advantek floor sheathing I was using is face-treated with water-proofing, so it should stand up to the elements until I have the roof on. I had hoped that they would hook up my temporary panel, but that, apparently, is a separate job. When I called CVPS on Monday, they expected to complete the job within a week.

After all of the sheathing was in place, I was in the crawlspace installing the bottom ends of the bridging and found myself looking repeatedly at the hatch. There is something about working in a space from which the is only one exit that is unnerving. Not that I expected a bear or the guys from ‘Deliverance’ to show up, but if they did…

The town was hosting a small tag sale and fair at the meetinghouse to raise money for it’s repair. The food was tasty and the folks were very nice. It was nice to see ‘Chris’ again, whom we had met previously at the bar of the Saxton’s River Inn. We also got to go into the meetinghouse for the first time to see first-hand that it needs a lot of work. It really does look like nothing has been done to it since 1817. We made a $50 donation, which I figured was the least we could do to preserve our view.

The LSW easily pulled her weight and made the job more enjoyable, and The Boy was well-behaved despite missing his nap and provided much-needed oversight from the sidelines.

Sadly, this was our last stay at the Saxton’s River Inn before the camping begins. Dinner again was excellent, and homemade donuts and pastries have been added to breakfast. I’ll miss the place – it feels like home at this point.

Next up: Raising the walls with my sister’s family.

Monday, June 15, 2009

Phase II: Introducing the floor, the neighbors and the Stress-o-Meter

(Pictured above, the crawl space where we'll lock up our booze when we're not there.)
LSW here, writing this blog entry on an old car insurance form found in my glove box. I'm sitting in the car, in the rain, in the parking lot of the inn in Vermont, drinking wine from a plastic cup and noshing on Sun Chips because, alas, once again the boy has fallen asleep in the car after a long day at the cabin site.

Today began Phase II of the Great Cabin Adventure. Some important details:

1. There are exactly 30 cell phone towers visible from the highway from Connecticut to Vermont. I know this because, despite my propensity to fall asleep in the car after 20 minutes, I was forced to follow the Vermonster because the generator wouldn't fit in my car, and the boy's carseat won't fit in the truck. In an effort to stay awake, I blasted Led Zepplin and we counted cell towers. Interestingly, as soon as you cross into Vermont, there aren't any visible towers. (Which would explain the lack of phone reception.)

2. I was the lucky recipient of the first job-site injury. A ginormous splinter the size of a sprinkle (or shot or jimmie, depending upon which part of the country you live in) lodged into my palm. Fortunately I packed the First Aid kit. The Vermonster received the second injury, although I wasn't there to experience it. Something about a hammer and a rusty bolt.

3. I learned first-hand how a house gets attached to a foundation. Something I've always been curious about, but not enough to ever ask.

4. We met one set of neighbors. They were very nice, but I was dismayed that the first thing the wife said was that the other neighbors, "are not nice people." I wanted to say, "For God's sake, I'm not getting involved in neighborhood politics before my damn house is even built!" But instead I said, "Well, we're building this place so we don't have to talk to anyone." The Vermonster was appalled, but really, let's just get this all straight right from the beginning. I'm trying to get AWAY from people, not make new frenemies.

5. I fear the Golden Egg has closed. Fortunately, the Inn at Saxton's River is now offering a better-quality breakfast. Not that it matters since from now on, we'll be roughing it at a campground.

6. I suppose I should make some sort of comment about the actual constructing we did. Well, here's the deal. The Vermonster is very, let's say, precise. (I know my father-in-law will agree with me on this one.) This is a good thing, especially when building something as large as a cabin. The devil is in the details, they say. So I can safely say that this will be the most secure, super-structured cabin in existence. I just hope that our marriage (and other family relationships) will survive this adventure. I know it took a great deal of inner strength for the Vermonster to trust me with a measuring tape and screw driver. I could feel him wanting to double-check my work but he held back for the most part. As the summer progresses, though, I don't know that things will be quite as polite. And so, I introduce the Stress-o-Meter:
This trip, the danger was low, although at the end, when it came time to put a tarp over the foundation, I thought I was going to lose it when the Vermonster started making hospital-corners on the damn thing instead of just tossing it over and tacking it with a few staples. Even the Boy commented that it looked like a big present.

Friday, June 12, 2009

Don_P, Deflection Expert

For those of you thinking "jeez, I wish I knew more about deflection in floor joists" - you're in luck: Don_P offered this treatise over at CountryPlans.Com:

"Floors are sort of unique in that we typically don't design them by strength but by stiffness. The limiting factor in most floor design is not bending strength or shear but deflection. The original deflection specification that appears as the code minimum is L/360. If a floor spanned 360" it would be allowed to sag 1" under full design load. This standard was initially to prevent plaster cracks in ceilings under a second floor. The use of 30 psf for "sleeping rooms" dates back at least 40 years. This predates our current lifestyles, water beds, mountains of stuff in a home, thin set tile, etc. Length/360 is a comfortably stiff floor in shorter spans, as they get longer it can become annoying. A sure recipe for disappointment is to design for 30 psf, L/360 on a span greater than about 15'. One simple design rule of thumb that came out of this research was that using 40 psf Live Load and designing for L/480 (25% less deflection than L/360) on the joists almost always works. The extreme example given in class was a 2X10 SPF 30psf floor framed 12" oc and spanning the maximum allowable 19'. The floor passes code but the vibration frequency would be 9 Hz, right in the middle of the most annoying range.

The floor frequency check is a way of looking at how a floor performs. In testing researchers found that people are very sensitive to vibrations in the 8-10 Hz range (I've read that this is the range of frequencies for functions in our bodies). They found that most people were comfortable if the floor vibrations were above 15 Hz. I'm not that finely tuned, what drives me nuts is to hear stuff rattling when someone walks across the floor. I'm not really happy with our 2x10 SPF floors that have roughly the same span as yours, my wife doesn't notice them. They check out right at 15 Hz so the average person, whatever that is, should be happy with them.

I've built long spans of 24'+ in a single lightweight engineered span , deflection of L/480+ a few times. In one case the customer complained, I hated the floor. In that case we had a very high vibration frequency but very little mass, it was too easy to get that snare drum vibrating. Having studied this some we added another layer of subfloor and screwed it on 8" centers in every direction. One of two things happened either the floor was made stiffer or we added enough mass to make it harder to excite.

To me that all gets pretty deep, the easy solution is to quit trying to span so far and don't push the limits with longer spans. Under a building its easy to break long spans in half, 1st to second floor requires some thoughtful placement of load bearing walls rather than a clear span building that can be cut up many ways. A stiff floor will still not feel like concrete underfoot until you get way out there. "

Wow. There's a man who knows from deflection.

Milestones and Deflections

Last night marked the first construction milestone: I cut the last check for the concrete work: $1,191.60, bringing the total to approximately $5,950. This was about $350 more than the estimate, but you may recall that I was warned in advance we might go over by 300 – 500 due to the slope of the land. The contractor was Charlie Record (Record Concrete of Chester, VT), and I’d recommend him without hesitation.

What would I do differently on the foundation the next time? Nothing, fortunately, and that surprises me. I’ve heard enough horror stories about contractors that I have to admit I expected to have at least small problems with anyone I hired. The fact that both the concrete and excavating work has been quick, professional and good quality has been encouraging. Of course, the fact that I researched the work up front, asked a million questions, and went in with a good idea of what I wanted probably helped. Here’s where experience as a business analyst and project manager pays off outside of work.

So far, at least.

Next up: Floor framing. After reading up and consulting a number of Internet Joist Span Calculators (including this one), I called Lavalley Building Supply expecting to order 2 x 10 x 16 Douglas Fir joists that I would space at 12” on center. And here’s where one of those pesky assumptions jumped up and bit me:

Salesman: What’s the span?
Me: 16 feet.
Salesman: You sure you want 2 x 10? Most people want 2 x 12 for 16 feet.
Me: The joist calculators I’ve been using say that Douglas fir should be good for 16.
Salesman: Oh – Doug Fir – yeah that would probably work. But we don’t have it – we’ve got spruce.
Me: Uh..

I told him I’d call back. After some research and a few questions, I determined that the framing lumber they had was lumped into a category that some calculators call ‘SPF’ – Spruce / Pine / Fir – which can be either northern (Lavalley’s was from Canada, eh?), or southern. It looked like I could still span 16’ with SPF 2 x 10s, but I was troubled by the comment that ‘most people want 2 x 12 for 16 feet’. The difference in price was about $9.50 vs. $16.50. My options:

1) Put in a beam and lally posts at 8’, and cut my span in half. This would be more work, but would allow me to use smaller joists.
2) Take Lavalley’s advice and go with 2 x 12s, which – according to the span calculators – should be much more than adequate. These would be heavier to work with and more expensive.
3) Take a chance on 2 x 10s, and insert a beam later if they proved inadequate.

What’s at stake? ‘Deflection’, apparently – the amount of flex or ‘sponginess’ in the floor. Apparently, we’re most comfortable with a deflection of about 1/2”; less and the floor is uncomfortably hard, more and there is too much bounce, causing the plates in your hutch to rattle when anyone moves.

In the end, I compromised by going with the 2 x 12s, spacing them 16” on center (which is standard) instead of 12”. This allowed me to reduce the number, saving a little work and minimizing the cost increase. The floor would have probably been fine with 2 x 10s at 12” oc, but the $200 savings wasn’t quite enough to risk it. And who am I to argue with experience?

Delivery is tomorrow, and we'll have about 14 hours to lay the sills, frame the floor, lay the decking, and then cover it with plastic until the next visit. Now the real fun begins!

Tuesday, June 9, 2009

Countdown to Phase Two

Once again last week I traded 6 hours in the truck for 1 hour on site. Remember my previous post about assuming nothing? Well I realized after our last trip that I hadn't verified the width of the walls, the size of the cellar hatch opening, the distance from the slab to the beam, etc. So, tape measure in hand, I left the house at 6:30 AM.

At least it was a nice day for a drive - sunny and about 75 - and, being Saturday, relatively light traffic. I arrived on site to find that the Excavator had completed the back-filling, removed the last tree that would block the drilling rig's access to the well site, and cleared the short stretch of brush to the nearest CVPS pole.

God this guy did a nice job. He worked a miracle on my (formerly) sloped property, and left me with a rock retaining wall to support the driveway and a nice rock border on the up-slope side of the driveway that tied into the wall we cut the driveway through. The septic job is his next year if he wants it.

I was surprised to find that the electrician had already put up the board for the temporary power, but disappointed to see that CVPS hadn't yet hooked it up. In a call to CVPS yesterday, they said the weather has been lousy and they hoped to have it in place next week - not good as we're supposed to begin building the floor this weekend. That will add 2 day's rental of a generator to my costs - about $120.

Turned out that the measurements were different from my assumptions, but not enough to have been fatal. No fox sightings this time, but I was visited by a bright yellow bird with black wings that I've never seen in the 'burbs.

Next weekend begins 'Phase Two'. Our goal: Lay down the sills and get the floor framed in preparation for help from my sister's family a the end of June.