Building a stick frame house in the woods in 90 days

[EddieWalker]

My understanding of venting an attic is to create airflow. There really isn't any way to control temperatures up there, or any reason to do so. You want it hotter in the attic then the surrounding temperatures so you get air coming in through your soffit vents and traveling up to your peak. This air flow is what keeps your rafters dry. If you didn't have this air flow, condensation would develop and moisture would remain up there causing rot and mold.

Foaming the rafters so that you cool and heat the attic with the house is something that seems to be pretty effective, but the up front cost is extreme and can take decades to pay back the investment from what you save over doing blown in insulation.

With standards increasing on what the R factor should be in the attic, I'm of the opinion that proven, traditional venting and R60 blown in insulation is the best way to insulate an attic on new construction. I'm not against foam, except for the cost. I have noticed that it does start to age and get a little rough over time, but if left undesterbed, it should probably be fine. One big advantage to foma over blown in is that you can go into your attic and not worry about desturbing your insulation and having to fill in the path that was created after going in in there. It's also nice if you have an attic HVAC system.

In the pictures of the roof, why didn't they install the fascia boards before the shingles? Are you going to use flashing over the edge of the fascia? How do you do this once the shingles are installed?

In the picture of the drain lines, it looks like a toilet 90 in the middle without anything that coud be a vent line. Isn't the vent supposed to be within a foot of the toilet? Usually in the wall, right behind the toilet.

I've worked with PEX, but have never installed a manifold for a whole house yet. I'm going to build my own for my parents house because everything that I've seen is either cheap pastic, or copper that I need to modify. The plastic ones have valves on each line that I like, but I hate the idea of using plastic and I have no trust at all that those valves will still work ten or twenty years from now. In every house that I've worked on with PEX and a plastic manifold, they seem fine, so it's just my opinion against them.

I've also decided not to put valves on each of my runs. Part of it is being cheap. At $12 each for good ones, they add up to hundreds of dollars that I just don't think need to be spent. Especially since the house main supply water cutoff is two feet out the door, right behind the manifold. The other reason is that most of the water lines will have valves at the other end of the line anyway. The only reason that I can see for valves on each line is to work on a line that is broke between the manifold and where it's going, or the valve at the end is leaking. Both are just as easy to fix with the entire house turned off anyway.

I'm curious and will be watching to see what your plumber does.

Thanks for all the great pics,
Eddie

 

[EddieWalker]

My understanding of venting an attic is to create airflow. There really isn't any way to control temperatures up there, or any reason to do so. You want it hotter in the attic then the surrounding temperatures so you get air coming in through your soffit vents and traveling up to your peak. This air flow is what keeps your rafters dry. If you didn't have this air flow, condensation would develop and moisture would remain up there causing rot and mold.

Foaming the rafters so that you cool and heat the attic with the house is something that seems to be pretty effective, but the up front cost is extreme and can take decades to pay back the investment from what you save over doing blown in insulation.

With standards increasing on what the R factor should be in the attic, I'm of the opinion that proven, traditional venting and R60 blown in insulation is the best way to insulate an attic on new construction. I'm not against foam, except for the cost. I have noticed that it does start to age and get a little rough over time, but if left undesterbed, it should probably be fine. One big advantage to foma over blown in is that you can go into your attic and not worry about desturbing your insulation and having to fill in the path that was created after going in in there. It's also nice if you have an attic HVAC system.

In the pictures of the roof, why didn't they install the fascia boards before the shingles? Are you going to use flashing over the edge of the fascia? How do you do this once the shingles are installed?

In the picture of the drain lines, it looks like a toilet 90 in the middle without anything that coud be a vent line. Isn't the vent supposed to be within a foot of the toilet? Usually in the wall, right behind the toilet.

I've worked with PEX, but have never installed a manifold for a whole house yet. I'm going to build my own for my parents house because everything that I've seen is either cheap pastic, or copper that I need to modify. The plastic ones have valves on each line that I like, but I hate the idea of using plastic and I have no trust at all that those valves will still work ten or twenty years from now. In every house that I've worked on with PEX and a plastic manifold, they seem fine, so it's just my opinion against them.

I've also decided not to put valves on each of my runs. Part of it is being cheap. At $12 each for good ones, they add up to hundreds of dollars that I just don't think need to be spent. Especially since the house main supply water cutoff is two feet out the door, right behind the manifold. The other reason is that most of the water lines will have valves at the other end of the line anyway. The only reason that I can see for valves on each line is to work on a line that is broke between the manifold and where it's going, or the valve at the end is leaking. Both are just as easy to fix with the entire house turned off anyway.

I'm curious and will be watching to see what your plumber does.

Thanks for all the great pics,
Eddie

 

[aczlan]

I've worked with PEX, but have never installed a manifold for a whole house yet. I'm going to build my own for my parents house because everything that I've seen is either cheap pastic, or copper that I need to modify. The plastic ones have valves on each line that I like, but I hate the idea of using plastic and I have no trust at all that those valves will still work ten or twenty years from now. In every house that I've worked on with PEX and a plastic manifold, they seem fine, so it's just my opinion against them.

I've also decided not to put valves on each of my runs. Part of it is being cheap. At $12 each for good ones, they add up to hundreds of dollars that I just don't think need to be spent. Especially since the house main supply water cutoff is two feet out the door, right behind the manifold. The other reason is that most of the water lines will have valves at the other end of the line anyway. The only reason that I can see for valves on each line is to work on a line that is broke between the manifold and where it's going, or the valve at the end is leaking. Both are just as easy to fix with the entire house turned off anyway.

I would avoid the plastic multipart manifolds if at all possible. I worked for a hotel with Manablock sectional valves (much like Viega MANABLOC Water Distribution System, Central Manifold System) and it was leaking between sections to the point where the threaded rods had to be re-tightened in ~3 years and several had to be replaced in 5-6 years.

Personally, if I ever redo my house, I will run a 3/4" trunk and tee off of it with 1/2" pex. Then I will re-setup a thermosiphon to keep hot water circulating along the truck. My problem with home runs is that they mean that I would need to run all the water in the line out to get hot water, so 60' of 1/2" pex vs 10' of 1/2" pex

Aaron Z

 

[architect]

as a final thought on fiberglass batt, walking my dog's this spring morning, 14 deg. F, looked at my cathedral ceiling roof, 2x 12 with air space, I could count EVERY 4 foot batt in the roof, because fiberglass SHRINKS, roof is 35 years old, but have been researching how to fix for many years. Ask your Contractors, building supply retailers and manufacturers how you keep your house tight if fiberglass shrinks over time, roof looks just like a view thru an infared camera. So this is why I have reserched how to fix, answer is foam or celulose (medium pressure) to fill voids including the air space, WHICH IS ONLY REQUIRED BECAUSE FIBERGLASS NEEDS, VENTILATED TO REMOVE WATER VAPOR. Water vapor leaves the house through bathroom venting and kitchen venting, should not be driven into the insulation. The Building Code requires venting with fiberglass, but no venting if you use foam.
Extra cost? how much energy will you pay for to compensate for fiberglass over the life of the house?

 

[architect]

here is an article written by the Owner/ Engineer at EnergyWiseStructures that I referenced before, note the last paragraph about the typical fiberglass insulated house and heat loss.


Richard Rue (RueEagles@aol.com) Energy Wise Structures

When choosing an insulation, don't just compare the R-values generated under laboratory conditions. "Although the fundamental heat transmission characteristics of a material or system can be determined accurately, actual performance in a structure may vary from that indicated in the laboratory (20.3)*." The R-value of fiberglass insulation can be particularly deceiving, because the published R-values are based primarily on conductive heat. "For all types of insulating materials, conduction is not the sole mode of heat transfer (20.3)*." "The total conductance is the sum of a component resulting from radiation and a component resulting from convection and conduction combined. These components can vary independently of each other (20.8)*."

Fiberglass insulation manufacturers don't like to test their products for all forms of heat transfer because "The movement of air through an insulation system, either by natural or forced convection, has a deleterious effect on thermal performance (20.2)*." "Typical leakage rates in most structures are 6 to 10 air changes per hour (22.7)*". "Air movement by infiltration through a building envelope must be limited if the space is to be maintained at a condition different from outdoors (21.9)*." "Control of infiltration is an important strategy to assure thermal comfort and minimize energy use in buildings (22.7)*." Some "insulating materials can reduce air infiltration and provide additional fire resistance and noise control. Insulation also increases interior thermal comfort by controlling interior mean radiant temperatures resulting in more uniform air temperatures within the enclosure. Proper use of insulation can reduce the size of heating, cooling and ventilating equipment, reducing initial costs as well as annual operating costs (20.14)*." "It should not be assumed that leakage through the building envelope occurs primarily at doors and windows where there are visible joints. Studies have shown that leakage attributed to windows and doors constitute only about one-fifth of the total leakage. Leakage cracks and openings in walls and ceilings, especially at intersections, although not as obvious, make a far greater contribution to total leakage. Up to 70% of the total leakage openings were in walls, and up to 67% were through the ceiling, depending on the particular structure (21.9)*." "The infiltration of a building is proportional to its leakage area. Reducing the leakage area by 20% reduces the average infiltration of the building by the same percentage (22.16)*."

"The effectiveness of thermal insulation is seriously impaired when it is improperly installed. Where there is a 4% void area in R-11 wall insulation, the heat loss is increased by 15%. A 4% void in the insulation of an R-19 ceiling results in an increase of 50% in heat loss.* When thin wall insulation is installed vertically with air spaces on both sides, air interchange around the insulation increases the heat loss by 60% (20.8)*." "To attain published or claimed thermal resistance values, it is essential to provide convection and infiltration barriers, to seal cracks in joints and to install insulation so that gaps and voids around and within the materials do not occur. It has been established that 3% edge gaps (stapling batts on the inside of the studs) around insulation can produce 30% loss in effective R value (20.2)*." "A continuous air infiltration barrier is one of the most effective means of reducing air leakage through walls, around windows and door frames and at joints between major building elements (22.11)*." "Effectiveness can be greatly reduced if openings, even very small ones, exist in the retarder. Such openings can be caused by poor workmanship during application, poorly sealed joints and edges, insufficient coating thickness, improper caulking and flashing, uncompensated thermal expansion, mechanical forces, aging and other forms of degradation." Even an excellent vapor retarder is of little benefit if it can be bypassed by a current of air (20.10)*." "The function of insulation is clear; it reduces energy loss from a surface operating at a temperature other than ambient. Optimum use of insulation can: (1.) reduce operating expenditures for energy, (2.) improve process efficiency, (3.) increase system output capacity or reduce required equipment capacity and its capital cost and (4.) reduce overhead, maintenance, fire and personnel insurance, and other plant expenses. The most important benefit of insulation is the energy conserved and resulting savings in fuel and power costs (20.10)*."

In the average structures being built using fiberglass insulation, it is not uncommon to see 45% total heat loss in walls and 50% in ceilings. These figures do not take into account any loss of R-values due to compression in the cavities, which can add up to an additional 30%.

*Note: The above quotations are taken from the American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) Fundamentals Handbook.

 

[pacerron]

Aaron,
I like your idea of a circulating hot water trunk line. It would work well in Pete's mom's house due to the location of the bathrooms, kitchen, and mud room. The circulating trunk would take some additional electrical energy to keep the water in the pipes warm but would be great.

However, I think Pete's family came from a Scandinavian country, so they may be long time users of "point of use" water heating. Most of the other parts of the world that have indoor plumbing, that I have been to have point of use. I have no idea if it is really any cheaper to operate than a well insulated central tank when you amortize the additional cost of a number of units, wiring them, etc. over a useful life period.
I have a large central plastic composite type tank that I purchased from my rural electric co-op that is now over 20 years old. I can turn the power off to it for 3 days and still get hot water for 3 showers. They have a radio controlled switch on it so they can turn it off during periods of super cold weather and give me a break on the electric rate because of it.
It would be interesting to see an inclusive cost analysis of point of use in one of our typically built western style homes that has so many bathrooms, kitchens, and mudrooms, all demanding instant hot water. Boy are we spoiled compared to the rest of the world.
Ron

 

[s219]

We just did spray foam and cellulose on the walls of our new house (2x6 framing) and then they blew loose cellulose into the attic (2x10 joists). Roof is ridge vented with lower vents hidden behind fascia boards tucked between cosmetic 4x6 rafter tails (clever design by builder). The area with cathedral ceiling had the rafter cavities filled with cellulose and used foam baffles to leave an air gap.

The system is very interesting, and I am impressed how tight the house is. Before the heat was turned on, temperature in the interior of the house was remarkably steady and independent of outside temp swings. Now that the geothermal is on, it takes very little run time to keep the house warm and I see *no* thermal patterns on the roof at all when we get snow, not even where they mounted can light fixtures in the cathedral ceiling (they are shallow LED units, so I suspect the cellulose got in behind them).

I can definitely see us recovering the added cost of the 2x6 walls and advanced insulation package very quickly, especially with the hot summers we have around here. Which is good, since it added a good chunk of $ to the cost of the house, on top of the chunk for geothermal.

 

[pacerron]

We just did spray foam and cellulose on the walls of our new house (2x6 framing) and then they blew loose cellulose into the attic (2x10 joists). Roof is ridge vented with lower vents hidden behind fascia boards tucked between cosmetic 4x6 rafter tails (clever design by builder). The area with cathedral ceiling had the rafter cavities filled with cellulose and used foam baffles to leave an air gap.

The system is very interesting, and I am impressed how tight the house is. Before the heat was turned on, temperature in the interior of the house was remarkably steady and independent of outside temp swings. Now that the geothermal is on, it takes very little run time to keep the house warm and I see *no* thermal patterns on the roof at all when we get snow, not even where they mounted can light fixtures in the cathedral ceiling (they are shallow LED units, so I suspect the cellulose got in behind them).

I can definitely see us recovering the added cost of the 2x6 walls and advanced insulation package very quickly, especially with the hot summers we have around here. Which is good, since it added a good chunk of $ to the cost of the house, on top of the chunk for geothermal.

s219,
Sounds like a good balance between cost and efficiency. Congrats.
How far under the ground and how long is your geotherm piping?
Ron

 

[MacLawn]

Eddie, you mentioned spray foam in attics that are heated/cooled with the house? Wha?? Man, I never heard of that before, therefore, it canno' be true!:wink:

Really, though, does this happen?

As for as the plumbing wall (what us geezers call them), I've usually framed up a one foot space for that, but I guess that has changed. Also, Eddie, I'm with you on not needing a manifold for turning off water. A main shut off valve should always be in an easily accessed place. And, if I had no more confidence in that new fangled pex stuff than to think I needed so many shut off valves, I'd just use copper.

 

[hawkeye08]

I would avoid the plastic multipart manifolds if at all possible. I worked for a hotel with Manablock sectional valves (much like Viega MANABLOC Water Distribution System, Central Manifold System) and it was leaking between sections to the point where the threaded rods had to be re-tightened in ~3 years and several had to be replaced in 5-6 years.

Personally, if I ever redo my house, I will run a 3/4" trunk and tee off of it with 1/2" pex. Then I will re-setup a thermosiphon to keep hot water circulating along the truck. My problem with home runs is that they mean that I would need to run all the water in the line out to get hot water, so 60' of 1/2" pex vs 10' of 1/2" pex

Aaron Z

If this turns out to be a problem, they sell little pumps that sit at the end (near faucet). When you want hot water, you press a button for the pump and it pumps the hot side into the cold side until hot gets there.