I rarely ever weigh in on comments but I have to on this one. I have a large acreage and have foamed in over 150 5” and 6” posts, along with numerous 4” and 6” square posts. Expanding foam works better and expands more if the temperature is above 70 degrees. I do not use , but have used, the SIKA prepackaged foam. I buy the foam I use in 1 gallon containers and mix with a drill, proper mixing is absolutely key!!! I have had to pull several end posts to put gates in and they hold great. Plus when I pulled the posts, I used a saws all with a 18” blade to cut off the foam. The post was completely dry, it had been in the ground 6 years and looked brand new still. I let the foam rise above the ground and use the saws all to make a small cone from post to ground so the water runs away. The foam is a bit more expensive then concrete but a lot less work! Concrete is porous and actually absorbs water like a sponge. Concrete never truly sets for years, the chemical reactions (hydration) is what causes it to cure. Concrete wants to absorb water and causes the wood to rot sooner or later. The weight on the bottom of the post is nice but the wood will eventually rot. Foam seals the wood, it will not rot or absorb moisture, sealing it. Foam “shrinking” is not a thing. The ground around it can shrink due to less moisture but the foam does not. Improper packing of the soil before placing or water saturated soil is the cause, not the foam. It can not shrink, it dries to a very hard substance. Concrete does the same thing, if the ground surrounding it wasn’t untouched soil or compacted properly, something better than a 2x4, it will move when the ground shrinks too. If you make your post hole a slight bell shape at the bottom, the frost locks it down. Ground freezes from the surface down. Doing this helps to stop any heave from a deeper freeze. Also, if you move the curing foam or improperly mix the foam, it can create voids . But it will not if you follow the instructions. If I get the mushroom around the post from the foam, I just add a bit of new foam to seal it and then shave it down when cured. Power and telephone companies have been using foam for years as it is far superior, my father worked for a Rural Electric Company for 35+ years and remembers when they first started using foam. He said it was a game changer. I have used foam for over 10 years on every type of fencing and miles of barbwire, we stretch the wire and have never had a problem. Sorry for the long post, I just read so much bad information and had to chime in.

Thank you for the video. When I used the foam, I poured it against the fence post and above ground level. That way the foam will coat the post and seal it against water. (It will slide down the post and you won't get that rolling effect that you see in the video.) I also went back a couple of days later with a utility knife (any knife would do) and trimmed the above-ground foam away from the post at an angle.) Finally, I think the bags cost me between $6 and $9. If you are digging a wide hole, consider getting two bags. At my age, it's a lot cheaper than a strained back! Thank you again and no, I don't work for them!

3 years ago I installed a fence using the same foam you tried. My exp. so far is very good. No movement and the fence is holding up through winters well. I used 2 bags per post because I used 3 foot deep holes with gravel beds at the bottom for a drain. I did concrete in some of the posts that were shallower due to ledge. The concreted posts all have 3 half inch rebar glued into the ledge. They don't move at all but took 10 times longer to install. Over all if you need a mail box or some free standing post that doesn't benefit from the concrete's mass, I'd use the foam.

My dad was an engineer and volunteered my brother and I to work with him in a family business, materials and welding engineering. We had a piece of equipment which had a plaque that had a statement, "one test is worth ten thousand expert opinions". Thats for the quality test.👍

Been using concrete for 50 years no need to dance with a new girl

Thank you! I was just about to use this foam to set a 10-foot gate post!

Thank you so much for doing this. Saved me time and money.🇨🇦

I have used foam in situations as a tech in telecom. I know how it works. One of the issues I have with using it to set posts is the weight that concrete adds to help with creating a lower center of gravity and a "foundation" for the fence. Especially is this crucial on gate posts. The extra weight of the swinging gates will inevitably cause those posts to lean.

I used this for My mail box post, all I can say is WOW and WOW Very solid and strong

i went 4 ft or 1.22m deep and used a 1.5 bags/hole, 1 set bag and .5 bag later as filler. make some sort of plastic cone (oil it) for the overflow, this will provide some downward pressure as the foam expands and help resolve the water issues mentioned. Both methods would be a lot stronger filled to the top too

I've installed many field entrance posts with 16-20' steel gates. I've used concrete and foam more recently. I would never go back to concrete. The foam is easy to work with and if done correctly, it protects the post and is every bit as stable.

Thanks, you make a great point between the two methods.

I had the ultimate test of fence posts set in concrete. During Hurricane Katrina in Mississippi, USA, posts broke off just above the concrete. Some posts shifted and others snapped laying about 25' down, sheered where the nails failed. I am a firm believer in concrete, though a pain to replace, but very sturdy. I am also a firm believer is using screws instead of nails as screws do not pull out unless they break.

If you add the foam correctly, its a much better seal against water. When you add the foam liquid you are supposed to make sure you pour it against the post on all four sides so that the post is coated with foam liquid even above grade. Also, lets fill the hole...lol..the foam should come above grade. We use a product by a different name (Fast2K), and its far superior to concrete.

very helpful! thank you from milwaukee! i am installing a hefty modern mailbox and was wondering and this helped loads lol

Thanks for the heads up!

Very illustrative, thank you for sharing

I was considering using the foam for a project this summer.. Sticking with concrete after this video. Thank you!!

Back when I did satellite installations here in the US for customers that didn't want the dish mounted on their roof, we used the foam on a pole installation and then put the dish on the pole/pipe. We have had tornados come through and completely destroy homes and while the satellite dish was gone and the pole maybe bent a bit, the pole remained seated in the ground.

Thank you! You've made our mind up.

Being American- I cannot comment on UK soil conditions. But here in the north east USA I dug a 36" post hole and used Post Fixit with a 4x4 post like you used. I mounted a substantial retractable hose reel that weighs about 40 Lbs. 3 years later, it has held with no noticeable tilting. You perhaps should have dug a deeper hole than you did. And yes, where I live we do have a high water table, but I make sure I tripe sealed my pressure treated post with deck seal-, paint, and a plastic moisture layer. I hope this helps.

Very Helpful! Thank you!

Up here in wet rainy Oregon, some of us use Pea Gravel for the post. It helps a few ways, like if the post moves even a fraction in the wind the gravel sinks and tightens the post continually never letting the post get loose. (Just keep the pea gravel capped off). Also, the water has a drain away from the post ground level so the water rot in that spot is no longer a problem. Another way it helps is that there is no concrete mixing! Many up here think it's faster and better.

So glad I found this before I put my new fence in. You've changed my mind about foam and concrete. Thanks for sharing 👍

I had a VERY different experience with the foam, no idea what brand but mine was a different color and my post are in super solid 4 years later. I remember I used extra and had foam way above ground lever in the end. Couple days later I used a foam board kind of knife and smother it out level. BUT I would just use concrete next time. Just seems better. lol

I used the foam product on two treated 6 ft posts and it worked great and both posts are totally solid. I used a post hole digger and that left a hole just a little larger than the post. The mix in both cased grew just slightly above ground level.

so glad you did this vid!

Thank you for testing this

How much difference do you think it would have made if you had filled the foam hole with a second bag or topped it off?

Good to know. Thanks!

Thanks from Kansas, U.S.A. Great informative video. I'm needing to set a couple gate posts and maybe new corner post. Think I will stick with the old quick-crete.

I've set posts both ways. I've had them set for several years now and both methods are rock solid. IDK what you did differently. I think the foam is certaily much easier for someone with a bad back or arthritis.

I.worked at Lowes for a few years and they had 5 gallon bucket with a post and filled with that same foam for a display. it had shrank about a inch over a couple years and was just wobbling around in the bucket ..they finally had to make a new one because it looked so bad!

Great video! I have seen that stuff in stores and always wondered if it was really any good. Only one comment; I'm a carpenter and a college carpentry instructor, a really common misconception is that moisture in soil will rot out your fence posts. Fact is, water in the soil does not cause your posts to rot. If you ever pull old posts out of the ground to build a new fence, you'll see that fence posts only have a rotten area of about 3-4 inches starting about 1 inch above the ground to about 2-3 inches below ground. This is because this is the area that sees repeated wet/dry cycles, everything above one inch drys out quickly and everything below 3-4 inches stays mostly moist and very little oxygen is present that far under the surface so no mould can survive and cause rotting. Rot is caused by a repeated cycle of wet/dry/wet/dry. 300 year old logs recovered from the bottom of lakes, rivers, and harbours are nearly perfectly preserved because they have been underwater constantly, they never saw a dry cycle, and thus exhibit no rotting. Likewise there is no such thing as "dry-rot", as I said a moment ago, rotting is the product of repeated wet/dry cycles feeding fungus that consumes the cellulose in the wood. If it was never wet, it would not be rotten.

Thank you, very helpful

THANK YOU FOR THIS!!!

Very explained. Thank you

I used the foam for my mailbox over a year ago, still rock solid!

Thank you! I would be really intrigued to see you do the same comparison with quick set concrete and post foam called "boa hold"

I think it'd be cool to see a strength test for concrete set metal or wood fence post. And in the test you'd do 1 post with one bag of concrete, 1 with 2 bags, and 1 with 3 bags. That way we can see if we're getting the same added strength per bag. I think using a winch with a tension meter might be a good way to test the strength. Just an idea I had. Thanks for the content!

Totally Random Watch but absolutely brilliant information, thanks for doing this test and great video.

Could you use this as the adhesive between multiple sheets of acrylic and polyethylene then shoot it? Like compress it all first to squeeze out excess and keep it from expanding too much then shave off the excess to the shape of a ballistic plate?

I used the Sika(foam stuff) to help straighten out a fence that was leaning from a hurricane. The posts were already in cement, but with some ratchet straps and good old fashioned muscle, we straightened it out the best we could and used the foam to fill in the gaps in the post holes caused from the wind. It worked well!

Your problem surprised me. I used a bag of Wika, and it set very strongly. The post is sturdy. My foam dried yellow color though, so may be different, even though it's also Wika brand. Also, I dug a very narrow diameter hole, maybe 6" to 7" diameter, and the foam overflowed over the top. I cut it off with a reciprocating saw, careful not to cut into the wood. Thanks for the demo.

Thanks for the information.

My fence / gateposts are all rotting out at ground level. The house has been there fifteen years or so. Interested in the pea gravel idea mentioned in the comments (quite a lot of rain where I live). Is there anything you could do to the bottom of the post that'd help it grip? What if I put stainless nails or some such into it before dropping it down the hole? I ask this as a home DIY guy. I'm not a tradie. Thanks.

Just this week I installed two fence posts using the foam. It worked great. The foam expanded so much I had to cut a large chunk of it off above ground. Posts are solid 👍. I used an old school post hole digger and dug 2ft deep holes for 8ft 4x4s.

great vid! I'm really interested in the sunglasses model you use..

I installed a treated wooden fence 21 years ago around my back yard. Holes were dug 3 feet down by 10 inches wide and filled up with crushed rock around 4 by 4 posts that were also treated. This year out of the 50 posts, I had to change 3 that were broken 2 feet down in the soil due to various impacts over the years. I was easi.y able to pull out the top portions of the broken posts but had to dig 3 feet down to remove the rest and installed new ones in thier place. No matter how well treated wooden posts are, they will all eventually rot and need to be replaced but the point here is that it took 21 years. That's pretty good in my books and also, rotted or broken wooden posts are much easier to change when back filled with crushed stone than when back filled with cement.

Glad I watched this before a foam mistake.

Just drove by our fathers old horse ranch in Springdale Oregon where as teenagers some 50 yrs ago we built fences. Railroad ties at corners and pressure treated 6"X6" posts every 8-10'. 2x6 pressure treated upper and lower rails with galvanized 5' wire mesh. Hand tamped each post with a shovel full of gravel,dirt and always using found rocks when available. Smiled as I drove by. Those were fences. key note we put one electric wire to keep horses from rubbing fences loose. Spend your money on treating the wood.

I don't know what you did differently from what I did, but I used an expanding foam product which looked like it came in the same packaging the one you used, but the foam was green. I used it six years ago on a post, and it is still as strong today as it was when I originally poured it in. I just went out after watching this and shook the post and it's still doesn't budge.

The foam I used had me pour it different and I was also supposed to cover it with first once it got to a certain height so it would adhere to the post and into the ground.

Thanks for the review I know now that I will be using Concrete mix. I noticed you did not mix the concrete Can you please elaborate I have always been i the habit of mixing in a wheelbarrow. thanks for sharing.

Thank you

Good job mate

Used the foam when I build my kids playhouse and the thing has become more and more wobbly over the years. Makes me wonder if the foam is shrinking or water is deteriorating the wood posts below grade. Initially it was very solid, easily as solid as concrete. Kind of disappointed but hey at least it will be easy to remove someday when they outgrow it lol

the foam is a neat idea, but the crucial part about concrete that helps keep posts stationary is the added weight

Great video.. thanks for sharing

Love the mix of units used in the UK. Inches, feet, and kilograms.

Like you, I was very skeptical of the foam product and it performed exactly as I expected it to perform. Thanks for posting this. Very helpful. That said, I would mix the concrete before pouring it in the hole. What you've done is a dry mix and dry mixes are much weaker than wet mixes.

thank you

I wonder if you could put that foam in a mold to make foam panels or bricks?

Great video. I made the mistake of setting some posts with that foam crap and of course they all fell down. Don't waste your time it doesn't work!

I set a bunch of posts directly in the earth. I tamped the earth back in around them as I filled in the holes. That was 10 years ago. They are all still fine. So that is another option. But it depends on soil type and wood type. In my case, the posts were all heart redwood. Also, the holes were pretty deep with as much wood below the surface as above.

All those grunts 🤣🤣 great comparison though!

Would it not also be true for the foam as with the concrete? You can fill it up and after expanding just cut the extent of it off and you'd have flat surface?

How long did you mix? I’ve only used it once but the two foot hole I dug and added the foam to, the foam came all the way out of the ground. Possible you didn’t give the mix enough time to activate?

So for the foam setup it doesn't touch the end grain then? Isn't that the most important bit?

As with all foam products, application is key. How well the products are mixed and how warm it is play major roles in the product performing as it should. The hotter the temps, the better.

One aspect has not been discussed. What sort of impact have the chemical composition of the foam on the nature?

You can also weather proof the bottom of the post before you burry it, or cover it in concrete. This will add a layer of protection and you can not see it as it is buried. A stain with sealer of just latex paint will do.

I've got a couple of 6 x 4 panels to put up. Will be using wooden posts what size posts would i need 7 foot?

I have used the foam to set a temp fence at a commercial construction site. Its is fast, the only problem is that after a heavy rain, the posts floatted and fell over. I had to got back and reset about half of the fence. A couple 100 ft.

I’m using it to fill the vent dukts from a Sentral Heat and Air Unit Removal. I went with window units.

Great video. Subscribed.

Righty ho I am buying postcrete, Thanks for this video It made my mind up

How big are you doing your holes to take 2 bags of mix I’ve always allowed 1 bag per post you use. 2 and still room for more

I think for either product, the setup could use some work on the post itself. Some kind of horizontal notches, some spikes/rebar extending out of it and a hole that's not smooth as well.

I think i will stick to using postcrete glad i saw this

Dry posts help with adhesion. You could add some lag screws to the post to make it harder to pull out. Pour the foam down the sides of the post starting at ground level so it doesn't leave a void around the post.

At least the wobbly post came out easy so he could redo it properly with concrete. Easy removal that's one pro!😅 Thanks for the video I won't be tempted to try that product myself.

I've never seen dry concrete mix poured into a fence post hole before. I didn't see any aggregate. Was that concrete or cement/and mix??

Great vid!

Curious if you actually followed directions.. The foam i used for a post, filled the hole to the top. It did t lookas if you poured equally around the post.

Thank you for the video

If you live in a climate zone that has winter…you have to pour the concrete so that the top is at least 8 inches below the surface then fill the rest with dirt. If you don’t do that the frost will grab the concrete and heave it up out if the ground. The dirt on top holds it fast against the frost.

Hey anyone know if I wanted to do a 4x4 post for string lights about 8 ft high, would sika be ok in this application? Also how deep and wide should my hole be for 8ft high post above ground? Thanks!

I had a buddy that would slip 8"-10" round pvc about 2' long into the hole, then put the post, then foam... And it hardened fast. I asked why he used the pipe inserts and he said its so that the posts can be moved and reused if needed. They dig up nice.

I've only ever used Postcrete or equivalent and, watching your video, certainly won't consider the foam! Looking at your level, do you use it to mix the Postcrete in the hole 🤣? I always mix/tamp with a piece of 2x2 to make sure it's wetted throughout.

good job

The trick i use with concrete is first mixing it in a bucket to proper consistency, i also add a couple 4 inch long x 5/8 inch lag bolts to the bottom of the post. And also filling the hole 2 inches below grade. That way you dont see the concrete when your done and it still enough to hold up to kids climbing the fence. Its a simple process that will save you headaches later

Good assessment but the main problem with concrete is that your wooden posts will only last for 6 years because the lime in the concrete will rot the post off where the concrete meets the post on top. You may achieve a little more longevity with angling the mix downwards and away from the post but concrete and wood are not a good in-ground mix. I haven't used expanding foam but since it is used to secure window frames into buildings and provide water seal, it may be a worthy option. Personally I use broken brick and block (good for recycling) with soil and they have been carrying 2 x 5 bar gates, I do however apply several coats of expensive wood treatment. I have posts many years old that don't need replacing! The other thing is that you have a lot of work on digging out and disposing of old concrete, when the posts have gone! Tried that one - never again! For field posts and wire fence I don't use either just a hole and a narrow spade. That works okay.

Would it be strong enough to use on a 6x6 Im building a punching bag stand and want the 6x6 in the ground then mount a wall mount for punching bags on the 6x6 my punching bag weighs 100 pounds.

Wet hole, plastic bag over post, pour foam between post and bag, it will expand and push the water out of the hole without causing an issue with the foam..

I d say there might be situations where this fancy foam idea could b useful. What they are is to b seen!

I would like you to dig up the concrete for the one post, I am curious to see how well the concrete mixed in the hole without actually mixing it.

I have used the foam. I set a mailbox post using foam about 4 years ago. Still solid. Not sure what you did wrong but be fair and try again.

I used the Pro Select deliberately to set a new mail box wooden post. Why? In case my town's snow plough guys ram it and break the post, a not unusual occurrence around here. If that were to happen, which would you rather dig out to replace it - the foam or a big block of heavy concrete? Enough said. For a fence, I'd use the fast setting concrete. For a mail box, the foam is more than adequate because there's no load on it.

I did my garden with 6' 4x4 posts in foam. It works well for the line and corner posts, but not for end posts, especially for a gate. NO GO for a gate.