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Akkula

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On 9/21/2022 at 8:15 AM, happycamper said:

TJIs are pretty common engineered lumber joists, made by Weyerhauser. They look like wood "I" beams. 

TJI I-Joists

 

11 7/8" is the depth - that's the most common floor joist depth, BTW. 360 is how big the flanges (tops and bottoms) are - not a big deal for you, they go up to "560" which is, basically, a 2x4 on each end. I try to not use those if I can because they are harder to saw. They are the most common floor framing product used in the West today. 

Eh. Cold formed steel is much harder to modify on the fly than wood is. The steel has to use specialized connection hardware to attach and you have to cut it just right. The joists above can have holes put in the web to let stuff pass through - the manufacturers provide max hole sizes. 

 

TJI® Joists – Trus Joist Technical Support

I would be shocked if floor trusses were economical at an 18' floor span. once TJI type joists became locked in, floor trusses started to struggle. Some contractors call TJIs "floor trusses" but... they are not - floor trusses look like this:

TrimJoist® Open Web Truss | TJ3121620 | Build With BMC

They are better for very heavy duty loads (not residential).

I would never go 24" on center for floor joists. That floor would be bouncy as hell and would vibrate a LOT - you would regret it for the life of the house. That's not an issue in roof framing but in floor framing it sure is. 

4 foot overex was what we would recommend when I was a geotech when the client didn't want to hear that drilled piers were required, lol. It is typically expensive enough that deep foundations are the more economical option. it also works a lot better. We'd always include both deep foundations and shallow foundation options if possible in soils like that. 

It is weird that they have a 4 foot overex but then require a structural floor. even a 2 foot overex would led a floating slab be ok. would it move? I mean, yeah. but that's why it's floating. You don't bear on it, it moves some, whatever. that's sort of the deal.  

I would strongly recommend drilled piers vs helicals. Drilled piers are a solid mass that extend down to a competent layer of soil. Installed correctly, they provide very little surface for expansive soils to thrust on. They also require far less hardware to attach. I know that Ludwig drilling in Lakewood does lots of piers, their sister company in Casper, Elko, does commercial and residential both. I'm not sure about Ludwig though. Helicals, due to, well, having a helix, provide a surface for expansive soil to push on. They're very good for uplift, or in tight areas, or areas where the soil is contaminated, or retrofit. But a good drilled pier crew can get ~25 18" piers done in a day, a small house like yours with no silly recumbent  corners or interior bearing would have +- 15 piers. That's typically how houses are done in expansive clay in Natrona county, which imported pretty much all of its construction practices from Denver. 

No. Start with an architect. Until you get dimensions, window openings, etc. nailed down, hiring an engineer is just burning cash. You can do whatever you want, it just costs money with an engineer.  The more nailed down the design is, the cheaper your engineering fee will be. 

 

What exactly does a 4 foot overdig mean?  Does that mean I have to dig it 4 feet below the footers?  How far would I potentially need to excavate if I would have a crawl space?  How much fill material would I need if I went that direction?  Would I need testing to confirm?

I am trying to see if it even makes sense for me to do traditional footers.  Thanks again!

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On 9/22/2022 at 3:10 PM, Akkula said:

What exactly does a 4 foot overdig mean?  Does that mean I have to dig it 4 feet below the footers? 

Yes. Excavate out 4' below the footings, a width of 4' to either side from the edge of the footings, and replace with better soil. It is not cheap. 

On 9/22/2022 at 3:10 PM, Akkula said:

How far would I potentially need to excavate if I would have a crawl space?  How much fill material would I need if I went that direction?  Would I need testing to confirm?

Just the footing depth and minimum crawl space clearance (I believe 24"? but deeper is better if you want ease of access).

On 9/22/2022 at 3:10 PM, Akkula said:

I am trying to see if it even makes sense for me to do traditional footers.  Thanks again!

TBH probably not. Lots of homes in Denver are built on deep foundations. 

Remember that every argument you have with someone on MWCboard is actually the continuation of a different argument they had with someone else also on MWCboard. 

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On 9/22/2022 at 1:35 PM, happycamper said:

Yes. Excavate out 4' below the footings, a width of 4' to either side from the edge of the footings, and replace with better soil. It is not cheap. 

Just the footing depth and minimum crawl space clearance (I believe 24"? but deeper is better if you want ease of access).

TBH probably not. Lots of homes in Denver are built on deep foundations. 

A GC I just talked to kinda freaked out about the helicals and said he thinks it would be a lot more expensive...but you warned about that.

I would have to dig 4 feet laterally on the footers and 4 feet below.  I may as well dig a bunch of lap pools and then fill them with a bunch of expensive rock.  

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On 9/22/2022 at 4:44 PM, azgreg said:

I'm a big fan of double stud walls.

 

Nice, I just googled it. Does that use cellulose?  What do you think of that stuff in comparison to other insulation?  Doesn't it slump down in the walls in time a lot?  I was thinking rockwool insulation but I am just beginning my analysis. 

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On 9/23/2022 at 3:56 AM, Akkula said:

Nice, I just googled it. Does that use cellulose?  What do you think of that stuff in comparison to other insulation?  Doesn't it slump down in the walls in time a lot?  I was thinking rockwool insulation but I am just beginning my analysis. 

I think cellulose is the best option for insulation. As for settling, it won't if it's dense packed properly. In the planning for our retirement home I considered rockwool, dense pack fiberglass, denim, wood fiber, and dense packed cellulose. My final decision is cellulose for a number of reasons. I also intend to keep my use of foam to an absolute minimum.

People, not a fan.

 

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On 9/22/2022 at 4:58 PM, Akkula said:

A GC I just talked to kinda freaked out about the helicals and said he thinks it would be a lot more expensive...but you warned about that.

I would have to dig 4 feet laterally on the footers and 4 feet below.  I may as well dig a bunch of lap pools and then fill them with a bunch of expensive rock.  

Yeah helicals are expensive. But structural fill is too. It really depends on the area. Sometimes you can get just well graded sand cheap and structural fill is easy, sometimes you have to use road base and it's in the 5 figures just for materials. Who knows? At least that GC knew what to worry about....

Remember that every argument you have with someone on MWCboard is actually the continuation of a different argument they had with someone else also on MWCboard. 

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On 9/23/2022 at 7:16 AM, happycamper said:

Yeah helicals are expensive. But structural fill is too. It really depends on the area. Sometimes you can get just well graded sand cheap and structural fill is easy, sometimes you have to use road base and it's in the 5 figures just for materials. Who knows? At least that GC knew what to worry about....

CDOT Class 6 road base is what they are calling for for fill materials in the geotech report for an overdig.

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On 9/23/2022 at 6:24 AM, azgreg said:

I think cellulose is the best option for insulation. As for settling, it won't if it's dense packed properly. In the planning for our retirement home I considered rockwool, dense pack fiberglass, denim, wood fiber, and dense packed cellulose. My final decision is cellulose for a number of reasons. I also intend to keep my use of foam to an absolute minimum.

I saw a good youtube on different insulation types.  I like the idea of the double stud wall.  I have seen some videos where they use an insulation netting to keep the blown in materials in place before hanging the drywall.  The biggest thing I don't really like is there is no great open area for electrical to run.  Having remodeled and added switches and things it is really nice to have some space there.  Perhaps you could staple the netting to the back side of the inside double stud walls instead of the front and that would leave you the width of a 2x4.  

Why did you choose cellulose instead of some of the other blown in products?

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On 9/23/2022 at 6:28 AM, Akkula said:

I saw a good youtube on different insulation types.  I like the idea of the double stud wall.  I have seen some videos where they use an insulation netting to keep the blown in materials in place before hanging the drywall.  The biggest thing I don't really like is there is no great open area for electrical to run.  Having remodeled and added switches and things it is really nice to have some space there.  Perhaps you could staple the netting to the back side of the inside double stud walls instead of the front and that would leave you the width of a 2x4.  

Why did you choose cellulose instead of some of the other blown in products?

Check out this post. This guy used the inner wall as a service cavity.

https://www.greenbuildingadvisor.com/article/framed-walls-and-air-barrier-membranes-for-a-pretty-good-house

People, not a fan.

 

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On 9/23/2022 at 2:13 PM, azgreg said:

If you're into rockwool batts here's a great example on using it.

http://ourhouseuponmoosehill.blogspot.com/2012/10/the-joy-of-insulating.html

This is a cool example.  I like how they insulated between studs traditionally vertically and then they used rolls in the void space horizontally between studs without any breaks for the 2x4s.  I don't really know the code for fire breaks.  I know sometimes you are required to put a stud horizontally inside a wall as a break so I am not sure how that works but using an insulation material that is impervious to fire can't hurt. 

 

Edit:--I actually found a great youtube that talks about fire blocking requirements from the building department where my mom's house will be.  Basically you can use insulation as a fire block.

 

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On 9/21/2022 at 6:39 AM, Akkula said:

Sorry, what does your first part above mean?  I am not familiar with the industry joist sizes and materials so I am not sure what sizes/joist types you mention.  As far as cold framing joists, I really like the open web designs they have.  It gives me more ability to modify on the fly if we don't think through something completely in the design phase.  What about lumber floor trusses?  Do you recommend against going to 24 inches on center?  Fewer materials is always good but I am sure there are some trade offs.

The geotechnical report mentions that we have to do a 4 ft  below the bottom of the final foundation level and also 4 ft laterally. It also says a structural floor is required because of a high risk of slab movement....I had forgotten that is why I had initially moved more towards a crawl space.  The geotechnical engineer said another alternative may be deep foundation or helical piers but they usually write the reports for overdigs.    The helical piers seem like a really good option to me after investigating them because I don't have to haul off and replace all that dirt to get no super good guarantees on stability anyway.  I believe I can basically almost leave the soil below undisturbed and basically build the house on stilts.  What are you thoughts?

I would really like to start by hiring a building engineer before I get into all the fine details with the architect.  Is that normally done if I have a fairly detailed sketch on what I want?  It seems like most people start with an architect...but I find more value in figuring out what is doable with an engineer first.  Perhaps they can help me on the ICF vs lumber decision.  

I love that we have so many experts on this forum in various areas!

Which company did the geotech? Goetech companies are not commodities. Some tend to be more conservative with their recommendations, and then some that do large % of their work with home building developers will be less conservative to reduce the cost for the builder. I would definitely have your geotech reviewed by a third party expert. Conservative geotech recommendations can cost you a small fortune.

Exterior ICF is awesome. Save on heat and cooling, reduced outside noises, protection against fires, tornadoes, hurricanes, etc. To get the most protection, you also need a concrete roof. You can also typically build a house much quicker with ICF than traditional wood framing. It’s about 10% more cost, but the prices are getting closer to regular framing. If you do your research, you can learn to do some of the ICF form installation. 

Anytime you’re in the foothills of mountains, you’re usually going to get some radon. I had it in South Reno and Fort Collins, and had the crawl space air pumped outside up in the air. 
 

 


 

 

kat.jpg

 

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On 9/24/2022 at 8:14 PM, Nevada Convert said:

Which company did the geotech? Goetech companies are not commodities. Some tend to be more conservative with their recommendations, and then some that do large % of their work with home building developers will be less conservative to reduce the cost for the builder. I would definitely have your geotech reviewed by a third party expert. Conservative geotech recommendations can cost you a small fortune.

Exterior ICF is awesome. Save on heat and cooling, reduced outside noises, protection against fires, tornadoes, hurricanes, etc. To get the most protection, you also need a concrete roof. You can also typically build a house much quicker with ICF than traditional wood framing. It’s about 10% more cost, but the prices are getting closer to regular framing. If you do your research, you can learn to do some of the ICF form installation. 

Anytime you’re in the foothills of mountains, you’re usually going to get some radon. I had it in South Reno and Fort Collins, and had the crawl space air pumped outside up in the air. 
 

Yeah, it may make sense to get another Geotech engineer to review but I am a bit inclined to take a more conservative approach in the foundation.  My preference is actually a deeper foundation, I think, because I don't have to worry about any foundation problems later.  There is a TON of foundation issues in that part of Colorado Springs.

I do like ICF a lot also..but after looking...I am not sure if it is right for us.  The installed cost is $31 per square foot of wall whereas a lumber framer told me he would do $10-14 per square foot of the entire house for labor.  The costs seem really high to me and there aren't a lot of other competing contractors who are comfortable with the system so prices seem higher.  The other thing about the ICF is that they have about an R22 rating for insulation.  I am a bit surprised this isn't higher.  The ICFs, however, have almost zero air leakage so that is really a lot of their benefit as well.

I may still change my mind, however.    

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I am also leaning towards using Densglass for the exterior wall sheathing instead of OSB or plywood.  They use it a lot here in Costa Rica because we have no OSB and we have a tropical climate.

Honestly, I am not sure why it isn't used as more of a standard.  It is basically mold proof, doesn't swell like wood, is easier to cut with a utility knife and snap, amongst other benefits.  I can also leave it exposed to the elements for a year without cladding which gives me a natural stopping point after framing if I want to let my mom go around choosing external cladding.  It is also mostly fireproof.

It looks like 7/16 4x8 sheets of commodity OSB at Home Depot are currently $15.60 per sheet.  Gold Densglass exterior wall sheathing is $24.23 per sheet.  My understanding, however, is I can put liquid flashing over the seams almost like joint compound and I may not need a house wrap.  

I see a lot of that fancy green zip OSB on a lot of the home building shows but nobody even has that in stock.  It is probably going to be closer in price to the Densglass (which is actually in stock).  

Densglass is used a lot in commercial structures, apartment buildings, etc. 

Does anyone see a reason why I should NOT use this?  Why isn't it used more?  Is it just people aren't comfortable with it?  This shows some wall assemblies and other technical data:

https://buildgp.com/wp-content/uploads/2018/11/DensGlass-Technical-Guide.pdf

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Hey @happycamper question.  You are not always required to have a structural engineer to build a house, correct?  As long as the build follows IRC, there is not a requirement to have an engineer stamp, correct?

I am confused on when an engineer is needed or when we can just rely on drafted plans.  

I am pretty sure I will need a good engineer on the foundation plan but I am not sure about the rest of the structure.  

What is the general rules on this for single family homes?  I am thinking of moving away from doing the ICF into double studded (thanks to this thread) but I am not sure how to specify out all those details for the framing.  Is that level of detail handled by the draftsman or do the framers just know what to do if you tell them?

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