---
product_id: 4877844
title: "MD Building Foam Backer Rod, Gray, 1/2in x 20ft for Medium Gaps | Closed-Cell Foam, Prevents Caulk Waste, Cuts With Scissors, Blocks Drafts Moisture Dust Insects, Indoor/Outdoor"
brand: "m-d building products"
price: "B/.14"
currency: PAB
in_stock: true
reviews_count: 13
category: "M D Building Products"
url: https://www.desertcart.com.pa/products/4877844-md-building-foam-backer-rod-gray-1-2in-x-20ft
store_origin: PA
region: Panama
---

# Easily cut to size Waterproof closed-cell foam 0.5in max gap fill MD Building Foam Backer Rod, Gray, 1/2in x 20ft for Medium Gaps | Closed-Cell Foam, Prevents Caulk Waste, Cuts With Scissors, Blocks Drafts Moisture Dust Insects, Indoor/Outdoor

**Brand:** m-d building products
**Price:** B/.14
**Availability:** ✅ In Stock

## Summary

> 🛡️ Seal smarter, live cozier — don’t let gaps steal your comfort!

## Quick Answers

- **What is this?** MD Building Foam Backer Rod, Gray, 1/2in x 20ft for Medium Gaps | Closed-Cell Foam, Prevents Caulk Waste, Cuts With Scissors, Blocks Drafts Moisture Dust Insects, Indoor/Outdoor by m-d building products
- **How much does it cost?** B/.14 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.pa](https://www.desertcart.com.pa/products/4877844-md-building-foam-backer-rod-gray-1-2in-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

- • **Effortless Custom Fit:** Trim with scissors for precise gap filling every time
- • **Weatherproof Durability:** Closed-cell foam resists moisture, insects, and outdoor elements
- • **Caulk Smarter, Not Harder:** Creates a sturdy base to prevent caulk waste and ensure lasting adhesion
- • **Seal Medium Gaps Like a Pro:** Perfect 1/2in thickness for reliable draft and dust blocking
- • **Versatile Indoor & Outdoor Use:** Ideal for windows, doors, driveways, and expansion joints

## Overview

The MD Building Foam Backer Rod is a high-quality, gray closed-cell foam designed to fill medium gaps up to 1/2 inch. Waterproof and weather-resistant, it prevents drafts, moisture, dust, and insects from entering your space. Easy to cut and install, it provides a durable base for caulking projects both indoors and outdoors, enhancing insulation and protecting your home year-round.

## Description

desertcart.com: MD Building Foam Backer Rod, Gray, 1/2in x 20ft for Medium Gaps | Closed-Cell Foam, Prevents Caulk Waste, Cuts With Scissors, Blocks Drafts Moisture Dust Insects, Indoor/Outdoor : Industrial & Scientific

Review: Perfect for Packing Large Gaps Before Caulking - Really happy with this foam backer rod. It arrived right on time and in perfect condition, no damage at all to the packaging. Works exactly as described and made packing large gaps before caulking so much easier. Great quality material and easy to use. Would definitely buy again for future projects.
Review: Excellent - Excellant

## 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 | B000BQWOC0 |
| Best Sellers Rank | #1,665 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #18 in Weather Stripping |
| Brand | M-D Building Products |
| Brand Name | M-D Building Products |
| Color | Gray |
| Customer Reviews | 4.6 out of 5 stars 5,402 Reviews |
| Global Trade Identification Number | 00043374714807 |
| Included Components | 1 Foam Backer Rod Roll |
| Item Form | Specialty |
| Item Highlight | Closed-Cell Foam, Prevents Caulk Waste, Cuts With Scissors, Blocks Drafts Moisture Dust Insects, Indoor/Outdoor |
| Item Type Name | Backer Rod |
| Item Weight | 9.07 g |
| Manufacturer | M-D Building Products |
| Material Type | Foam |
| Maximum Gap Fill | 0.5 inches |
| Model | 71480 |
| Number of Items | 1 |
| Number of Packs | 1 |
| Part Number | 71480 |
| Surface Recommendation | wall |
| UPC | 043374714807 |
| Unit Count | 1 Count |
| Water Resistance Level | Waterproof |

## Product Details

- **Brand:** M-D Building Products
- **Color:** Gray
- **Item Form:** Specialty
- **Item Weight:** 9.07 g
- **Maximum Gap Fill:** 0.5 inches

## Images

![MD Building Foam Backer Rod, Gray, 1/2in x 20ft for Medium Gaps | Closed-Cell Foam, Prevents Caulk Waste, Cuts With Scissors, Blocks Drafts Moisture Dust Insects, Indoor/Outdoor - Image 1](https://m.media-amazon.com/images/I/61UnawlcwQL.jpg)

## Available Options

This product comes in different **Size** options.

## Questions & Answers

**Q: Is it safe to use near hot water baseboard radiators? I want to use it behind radiator cover as a temporary fix for a cold draft.**
A: I suspect it would be safe if between the wall and the top cover of the baseboard, assuming you have standard baseboard covers like mine -- which never get super hot. It's foam, and will likely melt if too close to a heat source. To be on the safe side, I'd suggest first contacting the company directly.

**Q: Can you use barge glue and plastidip**
A: Call the manufacturer

**Q: I live in an apartment and i feel a draft coming through the cracks of my window would this help? Im trying to avoid using weather tape**
A: I purchased the medium backer rod and they are 1/2" thick. I think the one I purchased would be too thick to insert into the crack of your windows.  Maybe there is a smaller version that would work for you.

**Q: What caulking do u need for this ?**
A: I did use caulk as it was used to support a garage door seal as the bottom of the door.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Perfect for Packing Large Gaps Before Caulking
*by A***S on August 7, 2026*

Really happy with this foam backer rod. It arrived right on time and in perfect condition, no damage at all to the packaging. Works exactly as described and made packing large gaps before caulking so much easier. Great quality material and easy to use. Would definitely buy again for future projects.

### ⭐⭐⭐⭐⭐ Excellent
*by D***E on July 26, 2026*

Excellant

### ⭐⭐⭐⭐⭐ Perfect Core Material for Ear Posts—Must-Have for Owners!
*by T***D on November 15, 2025*

Though intended for sealing concrete gaps, this M-D Foam Backer Rod is an absolute game-changer for Doberman owners using DIY methods for ear posting. ​Perfect Density & Size: The 1/2 inch size and density are ideal for creating a stable, lightweight, and comfortable post core that is custom-cut to fit the ear canal perfectly. ​How to Use: The key to success is modification! It worked perfectly when wrapped in duct tape (or Zonas tape) to give it a firm, smooth exterior. This combination creates a far superior post than many specialized materials. ​Value: With 20 feet of material, this set offers incredible value, providing enough post material to last through the entire posting process for one or more puppies. ​If you are posting Doberman, Great Dane, or Boxer ears, forget the expensive custom kits—this backer rod, wrapped in tape, is the professional-level core you need. Highly, highly recommend!

## Frequently Bought Together

- 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)
- 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)
- Sikaflex Self Leveling Sealant, Gray, polyurethane with an accelerated curing capacity for sealing horizontal expansion joints in concrete, 10.1 fl. oz Cartridge

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**Shop now:** [https://www.desertcart.com.pa/products/4877844-md-building-foam-backer-rod-gray-1-2in-x-20ft](https://www.desertcart.com.pa/products/4877844-md-building-foam-backer-rod-gray-1-2in-x-20ft)

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*Product available on Desertcart Panama*
*Store origin: PA*
*Last updated: 2026-09-07*