Search  for anything...

Fast 2K Fence Post Mix and Concrete Alternative and Replacement for Fence Post and Mail Post Installs. 32.8 oz Bag of Expanding Composite Footing Compound

  • Based on 1,742 reviews
Condition: New
Checking for product changes

Buy Now, Pay Later


As low as $6 / mo
  • – 4-month term
  • – No impact on credit
  • – Instant approval decision
  • – Secure and straightforward checkout

Ready to go? Add this product to your cart and select a plan during checkout. Payment plans are offered through our trusted finance partners Klarna, PayTomorrow, Affirm, Apple Pay, and PayPal. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Selected Option

Free shipping on this product

Eligible for Return, Refund or Replacement within 30 days of receipt

To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.

To initiate a return, please visit our Returns Center.

View our full returns policy here.


Availability: In Stock.
Fulfilled by Amazon

Arrives Wednesday, May 15
Order within 1 hour and 42 minutes
Available payment plans shown during checkout

Size: 1 Pack


Style: Fence Post Mix


Features

  • SAVE YOUR BACK: Quick, lightweight patent pending technology replaces 80-100lbs of concrete with a lightweight bag that does not require messy mixing with water that requires cleanup & preparation for filling post holes
  • FAST & SECURE: Ready to build in 15 minutes, and mixes in seconds in place and in the bag. All that you need in a compact and lightweight 32.8 oz bag that mixes into a waterproof protection for your fence posts.
  • PRO TECHNOLOGY: It's the same technology used to set utility poles by the professionals. Now you can quickly and securely set your fence posts and mail posts with a minimum of fuss & mess securely.
  • EXPANDING COMPOSITE TECHNOLOGY: Fast 2K Fence Post Backfill uses an expanding composite technology which is stronger than traditional concrete. Designed to adhere to wood, Vinyl and metal posts.
  • HYDROPHOBIC TO PREVENT ROT: Unlike concrete which absorbs water which can damage metal and wood, the Fast 2K product is waterproof and hydrophobic which prevents water from getting into your posts, reducing rot, rust, deterioration and other water-related damage.

Material: Adhesive, Sealant


Brand: H.B. Fuller


Item Dimensions LxWxH: 1.5 x 8.5 x 7.5 inches


Color: No Color


Item Form: Foam


Manufacturer: ‎H.B. Fuller


Part Number: ‎254-20-S


Item Weight: ‎2.82 pounds


Product Dimensions: ‎1.5 x 8.5 x 7.5 inches


Item model number: ‎254-20-S


Is Discontinued By Manufacturer: ‎No


Size: ‎1 Pack


Color: ‎No Color


Style: ‎Fence Post Mix


Finish: ‎Vinyl, Metal


Material: ‎Adhesive, Sealant


Item Package Quantity: ‎1


Measurement System: ‎Metric


Included Components: ‎Multitool Accessory


Batteries Included?: ‎No


Batteries Required?: ‎No


Warranty Description: ‎Warranty


Date First Available: June 25, 2014


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Wednesday, May 15

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • PayTomorrow Financing
  • Apple Pay Later
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Top Amazon Reviews


  • Crazy stuff, but it works great!
Size: 1 Pack Style: Fence Post Mix
I got this to secure my mailbox post in the ground. The post needed to be dug up and raised recently and I came across this product when looking for some kind of cement to make sure it stays put after this second install. It was very easy to mix up and pour out. We were mesmerized by the process of the liquid becoming the hardened foam type end result. Very cool to watch. After about a half hour, it was pretty firmed up. A bunch had come up higher than we wanted, but we covered it with rocks to hide it. It seems very sturdy after several weeks have passed. Hopefully it holds up through the winter. It was a little hard to remove from skin, so make sure everyone helping is wearing gloves too - they'll thank you later. They do include them in the package which is convenient. Overall, this was an inexpensive and quick way to do the job. I recommend. ... show more
Reviewed in the United States on October 19, 2023 by TheGrayLady

  • This stuff is AMAZING!!
Size: 1 Pack Style: Fence Post Mix
Was not wanting to deal with the hassles of concrete to set a new mailbox post, the reviews on the internet of this product were all great so I gave it a try. Sooooooooo easy to work with!!! The post is SNUG with no wiggle room! Highly recommended!
Reviewed in the United States on February 13, 2024 by Karen B.

  • This product works great and was easy to use.
Size: 1 Pack Style: Fence Post Mix
This product worked great for my mailbox
Reviewed in the United States on February 29, 2024 by Melissa Braley

  • Light and Easy to use
Size: 1 Pack Style: Fence Post Mix
It starts firming up very quickly. You want to pour it in, get as much out of the bag as possible, and without getting it on you. I used it on two 4x4 fence posts to extend our fence line a little - it was easy to mix and pour, but I wish I had one more bag, as the hole wasn't completely filled when the foam stopped expanding. It did not feel as rock-solid as concrete, but if I need to dig it out later...it'll be much easier. I also used it for a 4x4 fence post going into an older 5x5 fence gate post hole in concrete. Dig up concrete, just to pour new concrete? Try to fit new concrete in the existing hole, around the fence post? That would never work. The foam turned out to be ideal for this use case. It grabbed the existing hole and the new fence post, feels very sturdy. ... show more
Reviewed in the United States on May 31, 2022 by Tremosian

  • Every aspect of this product is high quality.
Size: 2- 1L bags Style: Deck Post Mix
This product is definitely high quality. It is pricey however it works extremely well. I will say that you must have your project organized because once you’ve opened it(the bag to mix) and expelled it in the hole, time is of the essence. This is seriously impressive and some what over kill setting for just one post. One bag could actually do 2or 3 post holes if your well ready to steady them for 3 min. At once. ... show more
Reviewed in the United States on November 6, 2023 by Annette h.

  • Doesn't Last
Size: 1 Pack Style: Fence Post Mix
I have tried two bags of this and for me it just doesn't work. I love the idea of it and how easy it is to use. But it didn't last. I have a loose fence post. I cleared out the area around it down to where the old concrete was and poured in the mixture and watched as it rose like bread dough around the top of the hole and around the bottom of the fence. It felt secure at the end of the day. It came loose again in two days. I could move the fence post in the foam and within a week the fence was just as bad as before I tried it. Today a new bag arrived. I removed the old foam which comes off very easily. Cleaned off everything and tried again. The foam rose but didn't adhere to fence post in the hole. So now I have a loose fence post with a big yellow foam doughnut around it. Too bad. It was such a good idea. An expensive mistake - $50 for both bags and shipping and a bag of Sakrete would have cost under $20. ... show more
Reviewed in the United States on January 28, 2024 by myvureview

  • Was quite hopeful I found something good, took pictures and ended up giving up and buying regular old cement...
Size: 1 Pack Style: Fence Post Mix
UPDATE 1-10-15 Items were sent back (Amazon was superb, they provided a free shipping label to return the items and refunded the cost the day after the package was given to UPS). UPDATE 1-15-15 Amazon marked the items as 'received' and the credit still shows, major kudos to Amazon. Lousy is what this stuff was. I was excited and thought maybe their claim "Same advanced technology used to set utility poles for almost 15 years" might be a good indication but I can say categorically that claim is total non-sense. No way a utility company would ever use this, They might have TRIED it 15 years ago on one pole... So the details! (and I will upload pictures, I was VERY disappointed, so much so that I should have returned the empty containers to Amazon for a refund, but it is not Amazon's problem the products is lousy)... I had two posts I was putting up. These are to be posts to hold Just a hand railing, so they are not 'fence' posts, but a 6 foot fence post, holding a fence panel in the wind, (almost like a sail)? No way, this is an epic failure for that application. If you are 'effectively' OK with backfilling your post in with the equivalent of expanding spray foam, then this is your answer (not a good use, that is a pun)... So here is what I did exactly (pictures prove it!). I ordered 2 ($40) of the "Fast 2k Fence Post Backfill - 26 fl oz" packages from Amazon (after watching a video online and seeing someone use it). I read the instructions CAREFULLY (many times) and as you can see (from me wrapping my hand made posts in plastic wrap) I was concerned the blue foam might get on them and stick to them (I also put a bit of plastic wrap on walkway). The posts are regular 4x4 pressure treated that I have applied strips to, cut at an angle, and sanded and painted everything to end up with the posts you see. ONLY from ground level up is the entire design, below grade is regular 'fence post'... I also made a temporary bracket to hold adjustment to get the exact distance I wanted from both the stairs and edge of the walkway. I was thrilled at the idea of something 'encapsulating' the posts I had hand made (and therefore the posts lasting longer not dealing with groundwater rotting them out from below). Then wanting the posts in an exact spot I made up the temporary wooden alignment guide. Now comes the fun, after reading the instruction many times and being scared of the stuff, I CAREFULLY followed the directions. It was a 50+ degree day and I made sure the product was kept inside at the right temperature till I opened the bag. As you can see in my1st photo (that shows the post and the blue foam in the hole only) it did rise while it expanded but it never came up very far. I waited for over 30 minutes and it only 'rose' about 10" I then realized the hole might need a bit more so I prepped bag two and poured that on top (as directed). It too rose but not much (maybe 6 more inches) and you can see what that looked like in the photo that shows the step and foam and walkway edge. At this point I was out of foam and thought 'where will I get more, how much will it take" a guesstimate indicates this hole would have taken 4 bags and the other hole would have taken about 3 more. All said 7 bags at $20 a bag? How is $140 a good deal? NOW the 'epic failure' of this product. AFTER I carefully did not touch the post (It was very well supported) over and hour AFTER the second bag was poured and the surface of the foam was firm (not tacky) I tested the post. It moved a little bit and did not feel solid. I know the hole was not even half way filled so if it were totally filled with the Fast 2k stuff, maybe it would be OK. BUT if it were half filled with regular old cement that had cured there is no question the post would have been ROCK SOLID. I was bummed, I was not sure if I should 'chip' this foam 'junk' out (at this point I was very disappointed and the honeymoon was over) or what. I did not want to use cement then later find I should have removed the foam nonsense. I was NOT looking forward to trying to remove the post and then remove the foam and decided I would use REGULAR $4 a bag cement from the local home center. I went to the home center. bought 6 (50 pound) bags of quick crete and brought them home. I used a couple of bags and topped of the post that I had started using the 2k foam in, then on the other post I used only concrete. I ended up using about 5 bags total for a whopping $20. Had I used concrete from the start I would have used all 6 bags ($24). so $24 for a rock solid backfilled post or $140 for a post I would forever be worried about it getting 'wobbly'? I will NEVER use or recommend the use of this terrible product. I considered calling them and asking for help, but what can they do, it is a lousy solution for this application. I guess if it were a low fence post (that was in the middle of a run) and NOT under a lot of duress (say a short picket fence) MAYBE it might be OK, but a solid stockade fence, a corner post, an end post, or a gate post? absolutely a terrible idea! Don't get me wrong, Expanding foam is a great product and has MANY great uses but this is NOT a good application for it at all. ... show more
Reviewed in the United States on January 5, 2015 by E. Howland

  • Fast and Strong
Size: 1 Pack Style: Fence Post Mix
The product worked surprisingly well. Mixed and poured easy, and expanded within 2-3 minutes. After 30 minutes I came back to check the fence post and it was solid. Will use it again in the future for similar projects that I don’t want to bother with concrete.
Reviewed in the United States on January 7, 2024 by CP

Can't find a product?

Find it on Amazon first, then paste the link below.