Framing and Insulation question

[Shaun Wesley]

I know these may be stupid questions but hopefully someone more enlightened than me can answer this.

I am preparing a workshop in an unfinished area of my basement. It appears the previous owner framed a room but never drywalled it. Before I drywall it I wanted to add insulation between the studs but wanted to see if that was ok to do considering the wall has some form of insulation with a tin foil type backer already applied to the concrete walls. Is it ok to just apply regular insulation between the studs effectively doubling up the insulation?

Secondly, since it doesn't appear this room was framed during construction and was done by the previous owner can anyone advise if the green tinted board in the picture is actually pressure treated and ok to be used as a base plate? If it is not I rather change it out now before dry walling. I only ask because all pressure treated lumber I have seen has a brown tint and I have not seen one like this with green tinting. The rest of the base plates in the room are brown except this one wall.

Thought? Thanks in advance.

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[Bob Betker]

Shaun: CCA treated wood had a green tinge to it. It stopped being used about 10 years ago for residential use. If you think this work was done before the 2003/2004 timeframe, it's a good bet that it is CCA treated wood. Here is a link that tells you how to verify for sure if it is treated or not: http://www.ehow.com/how_6564152_identify-pressure-treated-wood.html.
I'd be more concerned about the insulation that is currently there. It looks like Reflectix or a clone; but that stuff isn't much good. It is meant to reflect heat back outside, in spaces like attics or crawl spaces. If possible, I'd consider installing 1" or better yet, 2" extruded styrofoam (XPS) sheets against the wall; that will help with any moisture issues with warm, moist interior air hitting a cold, concrete exterior wall. Then if you needed more insulation, put something like Roxul Comfort-Batt in the stud walls.

[Shaun Wesley]

Thanks for the reply. The home was only built in 2009 so it had to be completed after that. The previous owner sold it in 2011 so it had to be done between that time frame. I will check the link you provided. Just wondering if I need to rip that board out if it is not treated.

If I add regular batt insulation in between the studs will I have a moisture problem between the batt insulation and this tin foil covered insulation? I have access to alot of batt insulation already and would like to use that if it doesn't create any problems.

Here is a larger picture of the insulation in place if it makes it clearer as to what it is.
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[Roy Harding]

Isn't that interesting - pressure treated lumber up here in Canada is still green.

[Jeff Erbele]

I know these may be stupid questions but hopefully someone more enlightened than me can answer this.

I am preparing a workshop in an unfinished area of my basement. It appears the previous owner framed a room but never drywalled it. Before I drywall it I wanted to add insulation between the studs but wanted to see if that was ok to do considering the wall has some form of insulation with a tin foil type backer already applied to the concrete walls. Is it ok to just apply regular insulation between the studs effectively doubling up the insulation?

Secondly, since it doesn't appear this room was framed during construction and was done by the previous owner can anyone advise if the green tinted board in the picture is actually pressure treated and ok to be used as a base plate? If it is not I rather change it out now before dry walling. I only ask because all pressure treated lumber I have seen has a brown tint and I have not seen one like this with green tinting. The rest of the base plates in the room are brown except this one wall.

Thought? Thanks in advance.

273934

Your questions are anything but stupid. You want to avoid rot & mold, do-overs, double material expense and triple labor.

Green and brown treated lumber is still readily available today, although the chemicals used to treat it have changed. Home Depot explains the colors and chemicals and what is sold in various states or by regions in this link: First Look: Pressure Treated Lumber (http://ext.homedepot.com/community/blog/first-look-pressure-treated-lumber/)

I am not certain exactly what you have for existing insulation. The foil-faced, batt-roll appears like original construction. The vapor barrier is on the correct side, the interior. My hunch is your plan of adding batts between the studs would work just fine, but I don't want to steer you wrong.

[Bill Edwards(2)]

Isn't that interesting - pressure treated lumber up here in Canada is still green.

In Indiana as well!

[Bob Betker]

Shaun: As Jeff states, the major thing is to have the vapor on the warm side of the structure being insulated. From your original picture, I thought you had Reflectix, the second picture looks like foiled-faced fiberglass batt; which is much better than the Reflectix. The idea is to prevent warm moist air from touching the cold, dry outside wall or foundation. Since you have the vapor barrier facing the warm side, there shouldn't be a problem with condensation. I don't see a problem with you now placing batt insulation in the stud-walls.
I haven't seen green-tinged treated lumber in Northern Virginia in years, I'm surprised it is available in other parts of the country. You learn something new every day.
Good luck, Bob

[Shaun Wesley]

Shaun: As Jeff states, the major thing is to have the vapor on the warm side of the structure being insulated. From your original picture, I thought you had Reflectix, the second picture looks like foiled-faced fiberglass batt; which is much better than the Reflectix. The idea is to prevent warm moist air from touching the cold, dry outside wall or foundation. Since you have the vapor barrier facing the warm side, there shouldn't be a problem with condensation. I don't see a problem with you now placing batt insulation in the stud-walls.
I haven't seen green-tinged treated lumber in Northern Virginia in years, I'm surprised it is available in other parts of the country. You learn something new every day.
Good luck, Bob


Thanks for the info regarding the insulation. I will move forward with that endeavor. I did find a stamp on the base plate today while looking it over. Maybe this stamp means more to you than me and someone can tell me definitively if I can leave it in place or need to take it out.
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[Steve Milito]

It's kiln dried, heat treated, yellow southern pine.

[John Lifer]

Yep, not pressure treated, color looks like paint. Unless you have had water penetrate, I'd not worry about replacing. You ARE building shop wall right?
If there are moisture issues, solve those BEFORE you put your machines in the area. Or you WILL be sorry and dealing with rust.

[Jeff Erbele]

+1 on Steve's lumber stamp I.D. In case you are wondering, Rayonier is the forest product company that produced this piece of lumber.
+1 on John's advice regarding potential moisture issues. I think that is much more important than having pressure treated lumber.

During the 80's and 90's, I finished my bare basement with regular (untreated) framing lumber, helped a lot of friends & neighbors do the same and helped two relatives build their houses from the ground up. Nobody used treated lumber unless it was for a deck. Currently we are having a new house built and I have not noticed any treated lumber in any of the homes under construction or the builders' model homes.

If that was my basement and project and if I didn't have a moisture problem (the key factor), I would be inclined to insulate the studs, wire, plumb (if any) and drywall it and not worry. One thing I would pay attention to is making sure the sheet rock does not touch the floor. Gypsum is one big wick. Leave a 1/2 - 1" gap and cover that with base board, coved flooring or how ever you desire to trim it.

[James Conrad]

Based on the pictures provided, the foil insulation is not installed correctly to act as a vapor retarder due to the unsealed gaps at the floor. Can you identify the foil insulation and confirm it is an approved vapor retarder? Are the seams tape sealed, how is the seal at the top of the foundation wall? How well insulated are the joist bay areas over the foundation? Is the exterior of the foundation insulated? There are many factors to consider based on your location, climate and the basement environment along with meeting local code.

With that in mind and provided you have a "dry" basement condition you would most likely be fine insulating as is with unfaced insulation, Roxul would be my first choice due to higher r-values and moisture resistance. If you plan to drywall and laytex paint, that will act as a type 3 vapor retarder. Reducing air movement between warm and cold reduces the chances of moisture problems. You might want to have a conversation with your local code official as well.

[Shaun Wesley]

Based on the pictures provided, the foil insulation is not installed correctly to act as a vapor retarder due to the unsealed gaps at the floor. Can you identify the foil insulation and confirm it is an approved vapor retarder? Are the seams tape sealed, how is the seal at the top of the foundation wall? How well insulated are the joist bay areas over the foundation? Is the exterior of the foundation insulated? There are many factors to consider based on your location, climate and the basement environment along with meeting local code.

With that in mind and provided you have a "dry" basement condition you would most likely be fine insulating as is with unfaced insulation, Roxul would be my first choice due to higher r-values and moisture resistance. If you plan to drywall and laytex paint, that will act as a type 3 vapor retarder. Reducing air movement between warm and cold reduces the chances of moisture problems. You might want to have a conversation with your local code official as well.

Sorry for the late reply. The seems are not tapped and there are a few holes in the foil from moving stuff and hitting it. Should I go back through and tape the seems and holes? What do I use? Hvac tape? One wall is below grade and the other is not. This is a walk out basement. I will upload a picture of the top of the wall where the joists are so you can see. There is no insulation on the exterior of the foundation. The foundation is poured concrete and some form of black tar is applied to the foundation wall below grade. The foundation also has exterior and interior drain tile. I have had absolutely no water issues. Since you mentioned unfaced insulation are you saying I cannot use the JM faced insulation available at the BORG?

First picture is floor, second photo is celling and joists and the third photo just shows the one wall below grade where the HVAC enters. I assume holes like where this lines enter should be sealed up?

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[phil harold]

PLEASE NO FIBERGLASS
or at least do not consider it
you could get a mold problem pretty quick if you do not seal it corectly for you climate area/conditions
your basement may seem dry but that is because air is moving

concrete lets moisture in and out

Please read/search these links

http://www.buildingscience.com/documents/information-sheets/basement-insulation

http://www.buildingscience.com/search?SearchableText=basement+insulation

[phil harold]

To support my no fiberglass
review this article

http://www.buildingscience.com/documents/digests/bsd-103-understanding-basements/?searchterm=basement%20insulation

[James Conrad]

Some pics of the walls/area would be helpful, what region do you live in as well. You could use foil backed tape, or any non-permeable permanant joint tape, BORGs should have it.

If it were me, I would rip it all out, save the framing lumber and adhere 2" closed cell rigid foam to the walls, floor to cieling, maybe add 2 layers, reframe and leave the joist bays empty of any other insulation. I don't think fiberglass insulation is useful in a basement wall, it does not stop air movement and it will hold moisture, Roxul is a better option if you don't want to rip it all out.

[James Conrad]

To support my no fiberglass
review this article

http://www.buildingscience.com/documents/digests/bsd-103-understanding-basements/?searchterm=basement%20insulation

Good articles, worth reading!

[Shaun Wesley]

Some pics of the walls/area would be helpful, what region do you live in as well. You could use foil backed tape, or any non-permeable permanant joint tape, BORGs should have it.

If it were me, I would rip it all out, save the framing lumber and adhere 2" closed cell rigid foam to the walls, floor to cieling, maybe add 2 layers, reframe and leave the joist bays empty of any other insulation. I don't think fiberglass insulation is useful in a basement wall, it does not stop air movement and it will hold moisture, Roxul is a better option if you don't want to rip it all out.

I am in DC. The more I look at other sections of my basement and take the faceplate off the cable outlet I have noticed the entire basement was done with faced batt insulation and there is no visible vapor barrier. Meaning drywall, batt insulation and I can see the concrete foundation. Having spoke with my neighbor who had his home built at the same time this one was built by the same builder he instructed me the basement walls below grade have some form of black sealant on the foundation and foam boards applied on the exterior walls.

Does this account for why there is no visible vapor barrier on the interior walls? For the walls above grade, obviously there is nothing on the exterior side of the wall, is it fine the interior side only has batt insulation separating the concrete and drywall? Since the home is only a few years old it is hard for me to believe this passed inspection if it was not ok for there to be no vapor barrier..? Does this account for why the foil backed insulation in the unfinished area was no taped at the seams because it did not matter? Thoughts?

[James Conrad]

If the house was built in 2009 most likely the 2006 code was being followed, possibly 2003. At that time there was no requirement for insulation if the basement was unconditioned space. The black coating is a moisture barrier to help stop any exterior water from migrating through the wall, depending on how well it was applied, not a vapor retarder as used in other construction methods. The thing is with a concrete basement wall is that it is a giant heat sink allowing hot/cold and dry/wet to pass back and forth as conditions in the basement change and with the seasons. To mitigate this you need to isolate it from the conditioned space, one of the best methods is closed cell spray or rigid foam. Using that type of product stops thermal bridging and most of the concerns of condensation occurring in the wall cavity because you have isolated that heat sink. As mentioned before, fiberglass faced or unfaced does not sufficiently stop air movement. While it may not violate code then or now, it does become a matter of best practices. The articles that Phil points to have very good diagrams showing how to follow best practices.

To answer questions about vapor retarder, it was most likely not code required, and how we use and view vapor retarder has changed even from 2009. Against a basement wall, a vapor retarder is useless without insulation and vise versa. If you stop air movement and not the transfer of heat/cold, you will get condensation as it hits the concrete wall or the back of your drywall with enough temp difference. If you just use fiberglass, you are not stopping air movement... That is why rigid foam is so good for this application - it's a vapor retarder, insulator and if moisture does arise it won't breakdown or hold it.

[Ole Anderson]

Not uncommon to use PT on the plates in contact with the concrete floor, and untreated studs. Just in case you get some wicking or spills on the floor. Watching Mike Holmes in Canadian episodes, seems they reverse the vapor barrier and put it against the cool wall. I recall him saying that he felt that was one area where the Americans had it right.

[Bob Betker]

Shaun: I'm in the DC area as well. My in-laws have a similar setup on their house which was built about 10 years ago. In essence, they have put the vapor barrier on the exterior walls as you guessed. The black stuff is a type of mastic and it is meant to be a waterproofing material, primarily to stop water from wicking through voids in the concrete (hydrostatic pressure). The foam boards are designed to be a thermal barrier to the cold ground so that the walls don't sweat. This type of exterior insulation/waterproofing is good for 20-30 years before it fails.

If you were starting from scratch and money wasn't a problem, putting 2" XPS on the interior walls would be the best approach, it insulates and is moisture impermeable so no interior moisture would get to the concrete walls and condensate. Inside your stud walls, you can insulate with a batt insulation. I'd go with Roxul since it doesn't have the mold problems that occur if your fiberglass insulation somehow gets wet. That would get you to about R-30 range for the walls and the basement should be pretty comfy.

There is moisture-resistant, mildew-resistant drywall that you can purchase. I used it on my workshop and it only costs a buck or two more than regular drywall.
Lastly, make sure you check your rim-joist for insulation and air infiltration. Sealing that can make a big difference in how the house feels.
Good luck, Bob

[Shaun Wesley]

I picked up the Roxul insulation and have some followup questions.

I was going to pull down the foil backed batt insulation because I figured it defeats the point of using Roxul, since Roxul is mold resistant. I don't think it would be smart to leave fiberglass insulation pressed up against the concrete wall. Do I need to put a vapor barrier against the Roxul? This is in an unfinished room and only three walls are framed. The fourth wall is obstructed by the HVAC and water heater so it will be left exposed (covered by the foil backed batt). I figured if the Roxul is resistant to mold then what is the point of a vapor barrier? These walls are solely for holding the electrical and drywall and are not load bearing. Is there a benefit to having a vapor barrier if it doesn't cover the 4th wall anyway?

If you recommend using the vapor barrier how do I seal the electrical outlets? Can I just spray foam the holes in the box where the wires enter and tape the plastic vb over the front of the wall?

Thanks.

[phil harold]

your wood studs will mold if the roxul wont
you could use a borax solution applied to the studs to resist molding

yes foam the boxes

remember it is vapor retarder not vapor barrier
vapor is still going to travel thru you are only going to be able to slow it down
seal it the best you can
good luck with your project