--- product_id: 5587474 title: "MD Building Foam Backer Rod, Gray, 3/8in x 20ft for Small Gaps" brand: "m-d building products" price: "2632 kr" currency: ISK in_stock: true reviews_count: 13 category: "M D Building Products" url: https://www.desertcart.is/products/5587474-md-building-foam-backer-rod-gray-3-8in-x-20ft store_origin: IS region: Iceland --- # Waterproof closed-cell foam 3/8in x 20ft perfect gap fill Easily cut to size MD Building Foam Backer Rod, Gray, 3/8in x 20ft for Small Gaps **Brand:** m-d building products **Price:** 2632 kr **Availability:** ✅ In Stock ## Summary > 🛠️ Seal Smart, Save Big: The Pro’s Choice for Flawless Gaps ## Quick Answers - **What is this?** MD Building Foam Backer Rod, Gray, 3/8in x 20ft for Small Gaps by m-d building products - **How much does it cost?** 2632 kr with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.is](https://www.desertcart.is/products/5587474-md-building-foam-backer-rod-gray-3-8in-x-20ft) ## Best For - m-d building products enthusiasts ## Why This Product - Trusted m-d building products brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Precision Gap Filler:** Snug 3/8in diameter fits medium gaps flawlessly, reducing caulk waste. - • **Effortless Custom Fit:** Cut with scissors or utility knife for tailored sealing on any project. - • **Weatherproof Durability:** Closed-cell foam resists moisture, dust, and insects for lasting protection indoors and out. - • **Multi-Use Home Essential:** Seal drafts, insulate, and damp-proof doors, windows, roofs — your all-in-one gap solution. - • **Concrete-Ready Performance:** Ideal for expansion joints, creating a strong base for caulking that prevents erosion. ## Overview The MD Building Foam Backer Rod is a 3/8-inch diameter, 20-foot long closed-cell foam rod designed to fill medium-sized gaps with precision. Waterproof and weather-resistant, it prevents drafts, moisture, dust, and insects from entering your home while providing a sturdy base for caulking. Easy to cut and install, it’s perfect for both indoor and outdoor use, especially in concrete expansion joints, making it a versatile and durable solution for professional-grade sealing and insulation. ## Description desertcart.com: MD Building Foam Backer Rod, Gray, 3/8in x 20ft for Small Gaps | Closed-Cell Foam, Prevents Caulk Waste, Cuts With Scissors, Blocks Drafts Moisture Dust Insects, Indoor/Outdoor : Industrial & Scientific Review: good product - worked perfectly Review: Great to fill Concrete Expansion Joints! - So I've been looking around for a way to fix my concrete driveway. Unfortunately the concrete expansion joints have separated and have made a pretty big gap. After much research I found that I should use a backer rod to lay in the expansion joints and than use a self leveling chalk to seal it in. This will prevent any additional water from eroding the base material under the concrete. I needed a couple different sizes as the width of the expansion joints was different as you went up the length of the driveway. I found what I needed. The M-D Building Products Backer Rod. I bought both a 1/4 and 1/2 sizes. I like to tell people about my shopping experiences in this case I'll cut and paste this same review for both the 1/4 and 1/2 sizes I received (no big differences in these). Both the 1/4 and 1/2 inch arrived on time. They were packaged very well. Super light as you can imagine. The backer rod is like a foam material. It fit well into the expansion joints. A nice snug fit. This is exactly what I was looking for. Otherwise with as wide and deep as these expansion joints have gotten it would have taken a lot of self leveling chalk to fill them in. The material cut really easy. I use my utility knife but an ordinary pair of scissors would have worked just fine. I was happy with the quality. I felt confident when install it in the expansion joints that it would hold up just fine and do the job. ## Features - Quality Construction: This gap filler is made from high-quality, weather-resistant materials, ensuring long-lasting durability and performance. It effectively seals medium gaps between surfaces, preventing drafts and dust from entering your home. Suitable for both indoor and outdoor use, it withstands various weather conditions, providing consistent protection and improved comfort. - Concrete Gap Filling Excellence: Our product excels in filling concrete gaps, creating a strong foundation for caulking projects. Utilize this foam to effectively fill joints between surfaces, ensuring dependable adhesion for caulking applications that promise enduring durability and resilience. - Complete Gap Solution: This product provides versatile gap filling, preventing drafts and offering a sturdy base for caulking. Perfect for expansion joints in driveways and sidewalks, it can be twisted for larger gaps and easily trimmed with scissors to the desired size. - Effortless Installation: Enjoy a hassle-free setup by effortlessly pushing the backer rod into most joint openings until it fits snugly. Once installed, enhance the seal further by applying caulk on top—no need for messy sealants or adhesives. - Versatile Application: From repairing leaky roofs and window sills to addressing drafty doors, the Backer Rod is your go-to solution! Beyond sealing surface gaps, it excels in insulating, enhancing airtightness, and damp-proofing your home—offering multifaceted benefits for various household needs. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B000BQS90G | | Best Sellers Rank | #2,894 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #1 in Rope Caulk #36 in Industrial Sealants #1,439 in Hardware | | Brand | M-D Building Products | | Brand Name | M-D Building Products | | Color | Gray | | Customer Reviews | 4.6 out of 5 stars 1,665 Reviews | | Global Trade Identification Number | 00043374714647 | | Included Components | MD Building - 71464 - 2pk | | Item Form | Foam | | Item Highlight | Closed-Cell Foam, Prevents Caulk Waste, Cuts With Scissors, Blocks Drafts Moisture Dust Insects, Indoor/Outdoor | | Item Type Name | MD Building - 71464 - 2pk | | Item Weight | 17.01 g | | Manufacturer | M-D Building Products | | Material Type | Rubber | | Model | 71464 | | Number of Items | 1 | | Number of Packs | 1 | | Part Number | 71464 | | Surface Recommendation | surface_recommendation | | UPC | 043374714647 | | Unit Count | 1 Count | | Warranty Description | All M-D products are warranted to be free from defects in material and workmanship if installed and used in strict accordance with our installation instructions. | | Water Resistance Level | Waterproof | ## Product Details - **Brand:** M-D Building Products - **Color:** Gray - **Item Form:** Foam - **Item Weight:** 17.01 g - **Surface Recommendation:** surface_recommendation ## Images ![MD Building Foam Backer Rod, Gray, 3/8in x 20ft for Small Gaps - Image 1](https://m.media-amazon.com/images/I/61bhNB8Z9UL.jpg) ![MD Building Foam Backer Rod, Gray, 3/8in x 20ft for Small Gaps - Image 2](https://m.media-amazon.com/images/I/71glyJQDg0L.jpg) ![MD Building Foam Backer Rod, Gray, 3/8in x 20ft for Small Gaps - Image 3](https://m.media-amazon.com/images/I/818J6gOM3ZL.jpg) ![MD Building Foam Backer Rod, Gray, 3/8in x 20ft for Small Gaps - Image 4](https://m.media-amazon.com/images/I/81Py1S2524L.jpg) ![MD Building Foam Backer Rod, Gray, 3/8in x 20ft for Small Gaps - Image 5](https://m.media-amazon.com/images/I/81-xBTntOuL.jpg) ## Available Options This product comes in different **Size, Style** options. ## Questions & Answers **Q: how many feet come in a 3 pk?** A: Both INDIVIDUAL packs - the 3/8" and the 1/2"- are 20 feet long. **Q: no 1/4" one? either 20 or 50ft?** A: Not in this brand, but Amazon offers 1/4-inch backer rod in various lengths, from 10 feet to 100 feet, from other brands. Just search on "Backer Rod 1/4 Inch". **Q: can the backer rod be sliced for smaller openings?** A: I have not done that, but it cuts easily with a sharp knife or scissors, so you should be able to slice it to fit whatever opening you have. It's good stuff! **Q: Can his be used for exterior windows before caulking?** A: I used it to push into larger cracks in my driveway before applying concrete filler, and it worked great. I'm thinking that it should work well for filling in spaces around your windows prior to caulking. ## Customer Reviews ### ⭐⭐⭐⭐⭐ good product *by A***E on January 6, 2026* worked perfectly ### ⭐⭐⭐⭐⭐ Great to fill Concrete Expansion Joints! *by T***M on July 14, 2016* So I've been looking around for a way to fix my concrete driveway. Unfortunately the concrete expansion joints have separated and have made a pretty big gap. After much research I found that I should use a backer rod to lay in the expansion joints and than use a self leveling chalk to seal it in. This will prevent any additional water from eroding the base material under the concrete. I needed a couple different sizes as the width of the expansion joints was different as you went up the length of the driveway. I found what I needed. The M-D Building Products Backer Rod. I bought both a 1/4 and 1/2 sizes. I like to tell people about my shopping experiences in this case I'll cut and paste this same review for both the 1/4 and 1/2 sizes I received (no big differences in these). Both the 1/4 and 1/2 inch arrived on time. They were packaged very well. Super light as you can imagine. The backer rod is like a foam material. It fit well into the expansion joints. A nice snug fit. This is exactly what I was looking for. Otherwise with as wide and deep as these expansion joints have gotten it would have taken a lot of self leveling chalk to fill them in. The material cut really easy. I use my utility knife but an ordinary pair of scissors would have worked just fine. I was happy with the quality. I felt confident when install it in the expansion joints that it would hold up just fine and do the job. ### ⭐⭐⭐⭐⭐ SHOWS ACTUAL DIAMTER OF BACKER ROD diameter *by S***R on August 8, 2026* It is too bad that the by far the majority of bad reviews is due to not receiving the correct number of rolls. This says only one so all those bad reviews are for a different product. What I got works great. It was designed to fit a gap from 1/2" to 3/8". Anything smaller or larger, get a different size rod. I have include photo showing putting in backing rod on my garage trim board. It had a huge gap and I didn't want to waste the caulk trying to fill it up. ## Frequently Bought Together - M-D Building Products - Versatile Gray Foam Backer Rod - Essential Caulk Saver for Sealing Concrete Gaps, Expansion Joints, and Crack Filling, 3/8 by 20 Feet, (Pack of 2) (71464) - M-D Building Products - Versatile Gray Foam Backer Rod Set 1/2in x 20ft - Essential Caulk Saver for Sealing Concrete Gaps, Expansion Joints, and Crack Filling (71480) - Sikaflex Self Leveling Sealant, Gray, polyurethane with an accelerated curing capacity for sealing horizontal expansion joints in concrete, 10.1 fl. oz Cartridge --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.is/products/5587474-md-building-foam-backer-rod-gray-3-8in-x-20ft](https://www.desertcart.is/products/5587474-md-building-foam-backer-rod-gray-3-8in-x-20ft) --- *Product available on Desertcart Iceland* *Store origin: IS* *Last updated: 2026-09-08*