Fall Checklist: DIY Spray Foam Insulation with Dow Froth-Pak!

Manhattan Nest
Fall Checklist: DIY Spray Foam Insulation with Dow Froth-Pak!

This blog mini-series is a paid partnership with Lowe’s! Thank you for supporting my sponsors!

If you’ve read the title of this post and are thinking it’s already winter, then meteorologically yes, you’d be correct. BUT NOT ACCORDING TO ASTRONOMY, which places the first day of winter on December 21st this year, so take that! We’ll now move forward with the premise that it’s still fall and I’m right on schedule with wrapping up a semi-gargantuan to-do list of time-sensitive projects I really wanted to accomplish before this winter—at which point I will…uh…keep working, but on different stuff. Fun stuff. I’m excited for this winter stuff.

So. Having taken care of some overdue work like overseeding my grass, planting shrubs, pressure washing filthy siding, securing my garage/personal lumber yard, and wrapping up the major outstanding work on the side of the house, I’m turning my attention back toward the inside of the house. And there was a pretty major, glaring issue that I’m a little ashamed to admit. Behold:

It’s literally been YEARS since we’ve talked about it, but maybe you remember this room above my kitchen? It’s been through a lot…maybe this will jog your memory? Behold, again:

When I bought this house, it had been divided into two apartments and this room served as the upstairs apartment’s kitchen. I wrote about the preliminary demo work all the way back in 2013…and then evidently didn’t mention it again except in the context of the exterior work which involved removing the door and the window and replacing them with two little casement windows—an approximation of what I think that back wall originally looked like.

Anyway. At some point in there, I gutted the whole room. Part of one wall had been lost early on to a plumbing issue. Another wall because of the new window arrangement. The rest of the walls and ceiling were a material probably installed in the 1930s called Celotex, which is generally used as a rigid insulation board rather than a finished wall surface, but I digress. It all had to go—nothing original left anyway. Unlike the rest of the house, this section is 1 1/2 story—meaning there’s no attic above this room, and no reason the ceiling can’t be vaulted up to the ridge. Sweet!

Except…that was approximately 3 years ago. And aside from becoming a dumping ground for random crap (what else do you do when your mom sends you boxes of stuff you thought had long since been disposed of from your childhood bedroom?), it’s just sat that way. A shell full of potential, but not even approaching the top of any priority list.

Do you spot a problem here? I’ll give you a big hint that’s literally in the title of the post: NO INSULATION. I LIVE IN UPSTATE NEW YORK, PEOPLE. HEAT IS EXPENSIVE AND IT GETS COLD COLD COLD. WHAT A BAD CHOICE.

Seeing as this uninsulated room also became an unheated room as a result of other work, and therefore basically a barn atop my kitchen, this has meant a frigid kitchen below and the necessity of a space heater up here in the winter to prevent the pipes from freezing, as my bathroom is on the other side of one of the walls. Lest you feel like that’s overkill, I initiated this program only after the pipes had already frozen.


Now, I’m no energy efficiency expert (SURPRISE!), but this much I know. Hot air rises. Insulation keeps it from rising up and out of the house. I chose not to insulate between floors in my house (a subject of some debate in the renovation world), meaning that any heat from my kitchen/first floor rises up into this room, and then promptly out the walls/roof and away into the sky. You know that emoji of the flying stack of money? That’s kind of what I’ve come to picture emerging from my roofline around this time of year.

If you’ve worked on an old house, you’ve likely encountered the issue of insulation at one point or another. There are many options out there, each with their own pros and cons, but one that’s been gaining major traction for the last couple decades is closed-cell spray foam insulation. There are a lot of great things about it—it’s efficient, fairly quick to install, provides a vapor barrier, and even improves the structural rigidity of a building. That last aspect dovetails nicely with the fact that it fills irregular gaps and areas in an existing structure that might be difficult to access/fill with more traditional products like fiberglass bat. Old houses tend to have both weird areas like that and structural components that may not necessarily be a problem but also wouldn’t meet modern building standards, so the added structural strength—while it shouldn’t be relied upon to resolve an actual structural issue—is a nice bonus. To my knowledge, closed-cell spray foam application has always been the purview of professional installers, but now there’s an option for the ambitious homeowner or budding professional too! That’s me!

We are talking specifically about the Dow Froth-Pak system, available at Lowe’s! Right off the bat I want to make clear that this stuff is SERIOUS BUSINESS—while this post is intended to help others and share my experience, you absolutely must read the manual that comes with the kit, take all necessary precautions, and research anything you feel uneasy about before trying this at home. Don’t be stupid, basically. Let’s dive in.

When I first saw this product, I didn’t totally know what to make of it. Is it closed cell or open cell? Can someone like me even use it? Is it just a big version of those cans of Great Stuff? Can I do a whole room? A whole house? What is a board foot??! I will try to address all of these things, because there isn’t a ton of information online about it in one place.


So you’re thinking of using Dow Froth-Pak to meet an insulation need. There are a few things to consider.

How much area are you trying to cover? My room is about 13′ x 16′, with a vaulted ceiling about 10′ at the peak. Two of those walls are exterior walls that need to be insulated, as well as the whole ceiling. I haven’t excluded windows in that calculation, which is my lazy way to round up when figuring out what I need plus accounting for some waste. I think this product is good for a situation like mine—where you need to do ONE room or ONE ceiling or something like that, or you want to seal up areas like where floor joists meet the rim joist over a foundation in an entire basement. If the project is bigger than that, I’d definitely recommend at least quoting the job with a professional spray foam installer—it may actually be less expensive than buying the amount of kits you’d have to buy, and obviously save you some serious, potentially hazardous work.
Is there a product better suited to your needs? There are several compelling reasons to choose spray-foam insulation—but fiberglass bat, blown-in cellulose, or a number of other products may help bring costs down. In my case, I have irregularly spaced studs, meaning variably sized stud cavities, as well as a lot of weird shapes and angles  (due to post-and-beam construction and the vaulted ceiling) that would make installation of other products difficult. Obviously insulation works best when it achieves good coverage, and all of the irregularities with my framing would leave opportunities for lots of gaps and cracks with a product that can’t easily adapt to the shape of its space.
Are you up for it? If you’re not one for following directions or reading warning labels, avoid this. It’s not technically difficult but it can be somewhat physically demanding and messy. You also need to be at the proper stage of your project—which is AFTER framing work (including adding nailers or furring!), rough electric and rough plumbing are done. If you aren’t ready to put up drywall, you aren’t ready for spray foam insulation.


Dow Froth-Pak is closed-cell insulation, created by combining the contents of two tanks. One difference between closed-cell and open-cell spray foam is the thickness you want to spray. Open-cell spray foam is less dense, so you can fill a stud cavity and cut away the excess before installing your finished walls. Closed-cell is denser (with a higher R-value) and ideally should be a bit recessed in the stud bay—it can be cut back, but it’s more difficult. The amount of product you need will depend on the thickness you want to achieve. Each inch of thickness creates about R-6. So two inches = R-12, three inches = R-18, and so on. Local building code may require a minimal R-value depending on where you’re installing—always check.
Calculate your BOARD FEET. The Froth-Paks come in different sizes—to make it simple, let’s look at the Froth-Pak 210. The “210” refers to the number of board feet—which is a measure of volume, NOT surface area, but all you need to know to calculate it is the square footage of the areas you need to cover. It’s a simple calculation:

Length in inches x Width in inches  x Preferred depth of the spray foam in inches. Divide the result by 144.

So for example, an 8′ x 8′ wall with 3″ of foam would be:

96″ x 96″ x 3″ = 27,648 / 144 = 192 Board Feet

In other words, one Dow Froth-Pak 210 will provide about 3.25″ thickness of foam over an 8’x8′ wall.

AND THAT IS AS MUCH MATH AS I EVER WANT TO DO IN BLOG FORMAT. This is not a math blog. I’m sure those exist and I’m also sure I’m not interested.

I was hoping to get about 3 inches of spray foam on all exterior walls/ceilings, and my total board feet was about 1,350. Ideally I would have bought two Froth-Pak 650s and one Froth-Pak 210, but the 650 was out of stock so I bought all 210s instead. The product is the same, it’s just the amount in each kit that changes.

The total cost of that, by the way? A little over $1,800 clams. Add in various other supplies (we’ll get to that!) and it’s about $2,000 to insulate this room. To be honest I was excited to try the product and didn’t try to quote it out to a professional, so I can’t tell you how they compare cost-wise, but local labor prices can be all over the map so I’m not sure how helpful that would be anyway.


SO. With framing, furring (mostly just to compensate for old, uneven framing), and electric complete, it’s time to get down to it! Again—I AM NOT A SUBSTITUTE FOR THE MANUAL. I’m just a guy with a dream of a warm house in January.

Step 1: Check the temperature of your tank contents—this threw me for a loop so I’m making it item 1. There is a small temperature gauge on the side of the tanks, and a cut-out on the front of the box so you can read it without even unpacking everything. The interior contents of the tanks need to be between 75-85 degrees for optimal performance/mixing. This is a two-part system, so dispensing the proper mix is essential, and the temperature affects that. 75-85 degrees is WARM! Just sitting in my house, the tanks were reading much too cold so I placed the whole box on top of my cast iron hot water radiators (which are toasty to the touch but nowhere near enough to burn you), making sure to check them every 20 minutes or so as the contents slowly warmed up. NOTE: Dow recommends use of a particular heat tape or heat blanket for this purpose. I didn’t have them. Again, don’t be stupid—this had the contents heating at a pace of about 5 degrees per hour, so it took a few hours. Heating too rapidly/aggressively could cause an explosion, you crazy thing!

Step 2: Prep! If you don’t want it to get covered in spray foam, mask it off—ideally with something you don’t mind throwing away at the end. I had some already used 6-mil plastic in the garage that I used to mask off the chimney, the baseboards, and the door to the room. If I had more I’d have used it on the floor, too, but I just had this tarp. You also want to seal off the work space from the rest of the house as well as you can, and ventilate it (I opened all the windows and had a good cross-breeze, but the manual goes into good detail). I used my Bostitch pneumatic staple gun (currently on sale for $40!!) to keep my masking in place—it was a bit easier to put it up when working alone, and more secure than tape. Contractor bags worked nicely for wrapping the collar ties, which will probably be cleaned up a little and left exposed.

Step 3: Put on your costume! Like I said—this is serious business. Spray foam is both extremely sticky when wet and all kinds of toxic, so this is not a place you want to skimp. That means a disposable full-body suit, full protective eyewear, chemical resistant gloves, and a full-face or half-mask air-purifying respirator—I used this 3M one from Lowe’s, fitted with these cartridges. Small tip I wish I had: cover the face of your goggles with clear packing tape that you can remove and replace as needed. Dried spray foam can be removed from glass with a razor blade, but goggles are plastic and overspray may accumulate and make it difficult to see, and the spray foam will not come off without scratching them up too much to be usable. A headlamp may be helpful for darker spaces—I love this rechargeable LED Craftsman one (also on sale!).

Step 4: Unbox your Froth-Pak kit, ensuring the temperature gauge is between 75-85 degrees. The room and surfaces to be sprayed don’t have to be that warm, just the interior contents of the tanks. Shake both tanks for 30-60 seconds. You can shake them individually or use the carrying handle to hold them above the ground and rock them back and forth.

Step 5: Open the top valves on both tanks COMPLETELY. It’s very important that both valves are entirely open to ensure a proper mix. You should see the chemicals move through the hoses as the valves are opened—one is clear and one is brown-ish.

Step 6: Using the packet provided, apply some petroleum jelly to the inside face of the dispenser. This is primarily if you plan to use the Froth-Pak over multiple sessions and need to keep the dispenser free of dried foam between uses.

Step 7: Insert the nozzle into the dispenser gun. The Froth-Pak comes with two nozzle shapes—a blue “fan” nozzle and a clear “cone” nozzle. For a situation like mine, the fan nozzle proved the most helpful in terms of creating an even spray across a large surface. Dow gives you lots of spare nozzles that you may or may not use—but after you’ve started with one, it has to be changed any time there’s more than 30 seconds between sprays because the product cures so quickly and any blockage could screw up the ratio of the two parts. When the nozzle is fully inserted, you should hear a click and the yellow nozzle ejector will be clamped down.

Step 8: Pointing the dispenser into a container like a trash can (I used the box it all came in), purge the lines for 5-10 seconds. Foam should dispense pretty quickly.

Step 9: Practice! TAKE THIS PART SERIOUSLY. It definitely takes some getting used to. Using whatever you have available (I had a scrap piece of sheetrock), practice applying the foam as you will on your surface. You want to stay perpendicular to the surface, at an even distance (6″-24″ away), moving at an even pace in a side to side stroke. ALSO. VERY IMPORTANT. The foam only cures properly (and safely) if the layer of expanded foam is 2 inches or less. It will expand 3-4 times its thickness, so you want an even 1/4″-1/2″ coverage while you spray.  Inconsistencies in your pace, distance, or angle will result in an uneven application—and it’s harder than it looks, I promise. Especially with all that gear on and the pace you kind of need to keep up.

Step 10: Check your practice area. About 1 minute after spraying, it should have fully expanded and dried to the touch. It’s fully cured in 5 minutes—which is kind of bonkers.

Step 11: Start spraying! At this point you’ll probably want to change your nozzle. Using all the knowledge in your brains and safety equipment on your body, get to work. Perpendicular to your surface. Even distance. Even pace. Side to side. 1/4″-1/2″ thickness. Don’t panic. Because the foam cures so quickly, you can apply additional layers within minutes to build up to your final thickness—it’s better to do several thin applications than a too-thick application . To ensure you don’t run out of nozzles, you want to work fairly quickly. Avoid applying foam over foam that was just sprayed and is in the process of curing, and avoid build-up of foam beyond the depth of the wall, as this will need to be removed later on. Each Froth-Pak 210 took me about 20-30 minutes to mix, get set up, and use. By the way, the foam will stick to a lot of things including rigid foam boards—which you can see were already installed on parts of the back wall, and I just sprayed right over them since there was plenty of space in the cavity. Those foam boards should be R-10 on their own.

Step 12: The tanks will become increasingly lightweight as the contents are dispensed, which makes them more likely to tip over as you move. I’d highly recommend having a helper for this job (also in full protective equipment) who can help ensure the tanks stay upright, move them while you work around the room, and help identify areas that need more applied. As the tanks are nearing empty, you will notice the pressure change (kind of a quick sputtering) and the foam may look slightly different (darker, more viscous). STOP IMMEDIATELY. This foam is the wrong ratio and will not expand/cure properly—don’t think you can squeeze just a little more out, because those tanks are DONE. RETIRED. NO MORE FOAM 4 U. The tanks should feel empty, although there might be a little more liquid in there you can hear. That’s OK. It’s still done. I promise.

Step 13: Do not. Think that. You can just. Throw these things away. I said it all dramatic like that so you read past the word “done” (see item 12.). The manual explains a whole easy-peasy but super duper important disposal protocol, which is in place so you don’t inadvertently cause an explosion. I have nothing new to add to that so just please make sure you read it and do it, ok?

SO. IT HAS COME TO PASS. The whole insulation process took about 4-5 hours start to finish (including the masking and prep, but the tanks had to heat up for longer beforehand), and I think the coverage was basically as advertised so I didn’t need additional tanks. I found the technique of getting an even coating fairly challenging (you can see areas that look good and areas that look…not so good)—I do feel like I improved throughout the process, but since my first coat wasn’t especially smooth I didn’t give myself the best foundation. Like with painting, small lumps become bigger and bigger lumps with each new coat.

I was a bit nervous about fumes, but I left the windows open for about 12 hours after finishing up and I really don’t notice a smell when I go in there! Like…at all? Maybe something faint that could also be my imagination? I can tell you the difference is like night and day, heat-wise. It hasn’t been there long enough to know how it affects my bills/consumption (and those two casement windows are still drafty as hell—another thing on the ole to-do), but the kitchen below feels warmer and suddenly this room is OK to be in! It’s 30 degrees out! The street noise is also much quieter, and the whole room is immediately so much BRIGHTER—which doesn’t really matter because it’ll all be covered, but it makes it so much easier to work in especially in the evening hours which is when I’m the most likely to tackle stuff.

SO MUCH EASIER, IN FACT, that now I’m like…am I finishing this room now? To be totally honest I’ve forced myself to kind of stay away from it for a long time now just because there are so many more pressing things (I SEE YOU, KITCHEN. I JUST CAN’T AFFORD YOU. I’M WORKING ON IT.)…but now that it’s to this point, and I feel like I know what I want to do, it’s pretty much just a bunch of carpentry I could chip away at? Little by little? With supplies I mostly already have? And then? I could? Have guests? Like a person? Who owns a rather large house? And lives? Alone?

Dare to dream.

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Fall Checklist: DIY Spray Foam Insulation with Dow Froth-Pak!