Q&A: A Forum for Green Building Experts and Beginners

[Click map to enlarge]

Please register for a free account or sign in to ask and answer green building questions.

The usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration:
Under the box labeled "More explanation," look for the words "File attachments."
Click that, and you should be able to attach a photo.

Thanks for joining the conversation!

5 Answers

Converting an attic with blown insulation into an unvented cathedralized attic

I am planning a staged renovation project where i may defer the finishing of the attic space to an undetermined date in the future. To save money now, i am planning on just blowing cellulose to achieve the required R value (20 +inches). In the event we decide to make the attic space usable, we will pull out the blown in insulation and do an unvented insulated cathedral ceiling.

In Green building techniques | Asked By Alok Khuntia | Apr 22 15
7 Answers

Increasing the R-Value of an existing cathedral ceiling

When attempting to increase the R-value of a poorly performing cathedral ceiling, what is the most cost-effective interior application? There are exposed rustic wooden rafters every 4 feet or so that protrude from the ceiling 6".

In Energy efficiency and durability | Asked By Andy Kuss | Apr 22 15
12 Answers

Door flashing

Need to know if these pics tell a good or bad story. thanks

In General questions | Asked By RyobiJobSite | Apr 10 15
2 Answers

CFM and exhaust ducting

Hello folks,

Was going to install a 1500 CFM in our under construction build and suddenly found myself facing the MUA (make up air) dilemma.

I am told by my HVAC guy that for 1000 CFM, it would cost me $3200 for 2 dampers/louvers/ducting/upgrading the unit and one extra loop (geo). To upgrade to 1500 CFM, it would be close to $5200 which include all the above plus 2 extra loops.

In General questions | Asked By beenash khan | Apr 22 15
5 Answers

SIPs ridging

An acquaintance has a 5 year old SIPS house with visible ridging happening on the (unvented) roof. The builder (not me) went back and taped the seams. The question is whether there are other measures that the homeowner should do at this point, other than eventually adding ventilation to the roof? And does anyone have ideas as to what exactly causes the ridging?

In GBA Pro help | Asked By Bob Irving | Apr 22 15
3 Answers

iQ drive vs mini-split?

My last house (2700sf)was made with SIPS and had a traditional 16 SEER heat pump. It worked fine and despite a convoluted layout only had minor airflow issues. Now I'm building a smaller house (2000 sf) with double stud walls and better windows so I expect the envelope to perform better than my last house with 4" SIPS (climate zone 4 - east TN...go vols and all that stuff). I have been thinking of going with minisplits because they are all the rage...but with the inverter's used in Nordyns iQ drive couldn't it be close to as efficient?

In Mechanicals | Asked By Andrew Bennett | Apr 20 15
4 Answers

Ductless minisplit question

What models are available that will work at the lowest temperatures, it would be for a house in zone 4 (close to 5), about 4500HDD, at a design temp of -5F (-22C). The owner would likely keep the house temp at about 15C all winter, and the house probably has a heating load in the 20-30k range (at room temp so less at 15C).

Cost is of course a consideration, its an open concept two floor house with cathedral ceiling and unfinished basement,

In Energy efficiency and durability | Asked By Alan B | Apr 20 15
4 Answers

Improve efficiency and comfort of this room?

Please see the 2 attached pictures of a room that I would like to improve the efficiency of. The room is between the garage and the main house. I don't like coming in from the January cold only to be greeted by a cold room. I dislike paying the oil man even more that.

In Energy efficiency and durability | Asked By Michael Lee | Apr 22 15
21 Answers

Is it reasonable to use 3/8" PEX supply lines to all fixtures?

I am planning the plumbing system for my Net-Zero Energy home that is being built to Passive House standards. I will be using PEX tubing with a manifold system using home runs. I designed the house so that the bathrooms and laundry room are centrally located, making the supply runs pretty short. I want to minimize the amount of water and energy being used and low-flow fixtures provide plenty of water for my needs (2.2 gpm at sinks and 2.5 gpm for showers).

In Mechanicals | Asked By Gerald Blycker | Mar 11 14
1 Answer

Thermal bridging via a steel I-beam in an exterior wall

We have a masonry row house building with interior insulation (about R16) in New York city. The exterior of the building consists of 3 wythes of brick (about 12" thick). We are now building a steel frame deck. 2 steel i-beams will be inserted into the outermost wythe to support the deck. Does this present any kind of thermal bridging?

Note, the i-beam does not penetration the two innermost layers of brick npenetor the interior insulation. It only penetrates 4 " or one brick width in.

In Green building techniques | Asked By Daniel Herskowitz | Apr 21 15
Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!