48x39x14 shop build

[prichard]

Thanks Gus.

Friend of mine built a shop and installed a louvered exhaust fan. Turn on the fan and the louvers will open about halfway. Open the walk in door and it speeds up and the louvers fully open. He's suggesting that I install a louvered vent at the opposite end to allow the exhaust fan to suck out the engine exhaust or welder smoke that I want to remove.

I am struggling with cutting a hole in my building for the exhaust fan. I'm really struggling with cutting a second hole to let in outside air.......

Why not do like he did and just open man door or slightly raise overhead?

 

[ovrszd]

Why not do like he did and just open man door or slightly raise overhead?

Because it does nothing to ventilate the building unless a second opening is introduced.

I am hoping my heat source will make the exhaust fan more useful.

 

[prichard]

Yes, sorry I wasn't clear. I was only referring to the second opening.

 

[kevinwak]

Somewhere deep down on my to do list is to install a bathroom exhaust fan in my garage. I want just a low volume unit to run continuously to pull out the moisture from snow melting off of the wife’s van.

 

[ovrszd]

Somewhere deep down on my to do list is to install a bathroom exhaust fan in my garage. I want just a low volume unit to run continuously to pull out the moisture from snow melting off of the wife’s van.

Isn't this just like life? We improve the efficiency quality of our building and in the process create a problem.

 

[kevinwak]

Isn't this just like life? We improve the efficiency quality of our building and in the process create a problem.

Yupp.

 

[RayfromTX]

The new problem is created when the approach to the original problem doesn't address all the factors at play and/or is based on incomplete understanding of the issues. Even a tent has a potential for condensation issues. Remember not touching the ceiling if you didn't want a drip to start coming down on you? That's because you were introducing a surfactant from your skin to a surface that was wet from your breathing. The tent isn't the problem.

Tight buildings are able to perform at a much higher level but moisture must be understood and managed. This is worthwhile for living space but may be overkill for shop space. If you want shop space that performs like living space then you just have to build it tight and use proper levels of insulation placed in the right location for the system you are using. Then you can control the moisture levels with mechanical ventilation and/or dehumidification depending on your climate and circumstance. Dehumidification is required in the gulf coast region but mechanical ventilation is adequate in Colorado.

We used to build houses from wood without insulation. They leaked at the windows and in other places but they dried out quickly enough that they didn't rot. When insulation is added the drying potential is greatly reduced and now the leaks created rot. The leaks are the problem, not the insulation. Air tightness is the same. The moisture control is the problem not the air tightness. You can choose your level of performance but if you don't understand the science, you may make bad choices about how you utilize the products and components at your disposal. High performance buildings are a pleasure just like high performance cars but they require knowledge to build them safely.

A house doesn't have to breathe. Moisture has to be managed. Managing moisture by building a leaky building is akin to building a slow, poorly performing car because it is safer. That may be the right decision for some but the statement is not correct. You can't build a building too tight with our technologies but you can create a need for improved water vapor management.

In the 30s they solved the problem of moisture in buildings by ventilating the attic to allow it to escape. It was a solution that was appropriate to the time. Buildings were leaky and uninsulated or poorly insulated. That ventilation also allowed lots of heat to escape and created buildings that were often too dry. People then added humidifiers to control the moisture in the air. 80 years later there are much better solutions to these issues but they require us to look at things in a slightly different way. You can live in a tent or a refrigerator but the real solution isn't something half way in between.

The best ideas come from starting with the second law of thermodynamics and an understanding of the water molecule and applying those principles to our buildings. That sounds kind of crazy but that is the reality of building high performance buildings and it is no different than the solutions from the 30s. ASHRAE used the second law and an understanding of water vapor and developed testing in Minnesota that showed that the introduction of one square foot of attic ventilation for every 300 square feet of roof area would prevent the dangerous accumulation of water in the buildings of that era. We are still doing the same thing but consumers will need to catch up once again.

Beware of getting your info from marketing materials or insulation or HVAC contractors. Contractors are often well meaning but lack an understanding of the real issues and are influenced too heavily by marketing.

 

[ovrszd]

I appreciate your time in this discussion. I hope you appreciate that your input is beyond my capability to fully cprehend. I think this is common in society. So society is left to make their decision based on economics. Sad, but true. So to reach us you must include economics in your offerings.

Thank you very much for your input in this discussion. I'm learning, although slowly.

 

[RayfromTX]

Richard
I understand. It took me a year of full time study to get a background knowledge of the issues and then a 6 hour lecture by one of the top building science professors of our time to congeal it into gut level understanding. I then spent a year developing the ways to overcome the challenges with cost effective strategies and about another 2-3 years before all my buildings were transitioned to the new system. I refused to implement any methods that were not economically viable even though the budgets of my buildings could sustain methods that are not able to be strictly economically justified. As I have said before, this is a big subject and it can't really be covered in posts on a tractor forum but I will say this;

2" polyisocyanurate foam board which is one of the exterior insulations I use is around 65 cents per square foot. That is more than fiberglass but less than spray foam. As a part of an overall system, it can be done for a very reasonable cost. The measures we currently use to air tighten and insulate buildings are mostly a hodge podge of whackamole where we address each problem that is created by applying one more layer of sealing technique or strategy. The things I no longer need to pay for on my buildings include, sealing at the plate line, sealing wire penetrations, weatherstripping and insulating attic access, IC rated recessed cans, sealing recessed cans to the drywall, sealing and gasketing electrical boxes, attic ventilation and other things. The biggest benefit however is that there is no safer way to build a building from a durability and indoor air quality standpoint and the cost of no failures can't be overstated.

But I get it. There is a lot of new info to digest and it takes time. Just take your time and if you are interested dig a little deeper as time allows. What matters isn't knowing what product to use where. What matters is to understand the forces at play and how they affect our buildings. After that, the rest becomes clear. I must admit that I would have gotten to a better understanding sooner if I had ignored products and strategies when I first started trying to learn about this and focused on the basic science instead. The implications of the Second Law are the key. Enjoy the journey.

 

[ovrszd]

Thanks Ray.

I think comsumers are swamped with advertising gimickery
Then add the builder's familiarity with a method he's comfortable with. The end result varies and further confuses the consumer.