How To Insulate Behind Shiplap

Whether you’re renovating your house or building it from scratch, one common question you may find yourself asking is, how to insulate behind shiplap.

Adding insulation has many benefits and the process is not difficult at all. With some understanding and knowledge of the topic, you can easily insulate your shiplap walls.

To insulate behind a shiplap, follow these steps:

  1. Between the shiplap and studs, install a layer of home wrap.
  2. Using a can of spray foam, seal the gaps between the wall and window frames, as well as the door frame and wall. 
  3. Check the distance between studs using a measuring tape. Now, trim the fiberglass batt accordingly. 
  4. Use the fiberglass batt to cover the inside cavities by inserting it snugly between the studs. 
  5. Use a polyethylene vapor barrier to cover the fiberglass insulation. 
  6. Finally, install the shiplap panel over the polyethylene vapor barrier.

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What Exactly Is Shiplap?

Shiplap is a construction material used in interiors of houses, sheds, and barns.This material was initially used as a shipbuilding material back in the Viking Age. It also served the purpose of waterproofing the ships. 

Essentially, it is a specific type of wooden plank with a subtle, homespun texture. It is quite visually appealing and is a popular choice for interior finishes as it has a natural, rustic look. Each plank of shiplap is prepared in a way that allows it to be installed with a neat and tight fitting. 

Do You Need Insulation With Shiplap?

When installed, shiplap planks have an overlapping effect which creates a system called tongue and groove. This fitting method actually serves two important purposes.

Firstly, it forms a seal that helps protect against weather and wind. Secondly, the wood is able to go through seasonal changes of contracting and expanding without being prone to cracking.

Shiplap is a tough material and has insulation properties of its own. In fact, it was originally used to shield ships from cold and harsh temperatures. So, you don’t have to insulate shiplap panels in your home, but it’s definitely advised to. 

However, if you want to regulate your home’s temperature and get some savings on heating and cooling bills, then insulation is a great way to do so. In simple words, quality insulation can block heat from coming into your house during the summer, while holding heat in the winter.  

Can You Put Insulation Behind Shiplap?

Yes, you can put insulation behind shiplap and it is quite easy to do so. The insulation can prevent humidity, deformation, mold and damage. You can use different materials for insulation including fiberglass batt, foam, spray foam, as well as mineral wool.

Do I Need A Vapor Barrier Behind Shiplap?

Good quality shiplap is weatherproof, and the overlapping effect also helps make it airtight. However, it is usually a good idea to install a vapor barrier for added protection.

A vapor barrier can help seal any possible areas from which air can penetrate through. An expanding spray foam can also be used to do so. 

How To Insulate Shiplap Using Fiberglass Batt

1. Install Home Wrap

A home wrap is a waterproof material that can be used as a barrier for weather-resistance. It allows air to pass through but does not let water get into the interior wall cavities. Plus, it lets water vapors from the internal side pass outside. We recommend DuPont Tyvek HomeWrap from Amazon.

Installing a home wrap is an important step as it prevents moisture from getting into the studs. It also allows the fiberglass to work properly by saving it from moisture. This protective membrane can protect shiplap even if its soaked. 

If there is a sheathing layer present, you can install the home wrap between the shiplap siding and the sheathing. 

2. Seal Gaps Between Window Frames And Door Frames

Next, look for any gaps between the door frames and window frames. You can use a can of spray foam to seal the gaps properly. It’s a good idea to leave the foam to settle in and dry overnight. Loctite is our favorite.

If there is any excess dried foam, you can simply trim it off using a knife or cutter. 

3. Check The Distance Between Studs

Using a measuring tape, check the distance of the studs starting from the floor to the ceiling. 

4. Trim Fiberglass Batt; Insert It Between the Studs

It’s time to trim the fiberglass batt according to the measurement you took. Simply add a quarter or half an inch to the measurement and trim the fiberglass batt accordingly. The increased width will make it easier for the fiberglass batt to fit in the wall cavity. 

Now, insert the fiberglass batt between the studs. Remember to keep the paper or foil side towards the inside of your house. Make sure all the wall cavities are covered with the fiberglass batt. 

5. Seal The Fiberglass Insulation

Next, you can add a polyethylene vapor barrier as a seal. This acts as a breathable and protective layer that prevents trapped moisture and potential mold issues. We like this Nasatech vapor barrier.

You can use staples to keep the polyethylene vapor barrier in place. 

6. Install Shiplap Panels

Finally, you can install the panel horizontally or vertically, depending on your preference. A horizontal installation can make the room look wider and bigger, whereas a vertical installation can create a higher, elevated effect.

Other Options For Insulation Behind Shiplap

1. Rigid Foam Insulation

You can use rigid foam combined with can spray foam as an effective insulation with a high R-value.

The R-value is a unit used to measure the level of thermal resistance you can get from insulation. In simple words, a high R-value means a highly effective insulation performance. Some states have building codes that require a minimum R-value for insulation.  

One problem associated with fiberglass batt is that it requires a lot of digging in the wall cavity to let you achieve a high R-value. Rigid foam allows you to achieve this value without digging a deep wall cavity between the studs. 

2. Closed-Cell Spray Foam

You can achieve the highest R-value using closed-cell spray foam. One major advantage is that this can be used in the smallest wall cavities as well.

However, this option also happens to be the most expensive one. Furthermore, you can’t install this at home yourself as it requires professional help and special equipment.

3. Mineral Wool

Mineral wool is another material you can use for insulating shiplap. It is similar to fiberglass batt and can be installed using the same method. 

The process of making mineral wool is a lot like making cotton candy. This fibrous material is created by spinning rock or mineral materials at a high speed and temperature. It also has flame-resistant properties. One downside of mineral insulation is that it can be difficult to achieve a high R-value with it. 

Should I Leave The Insulation Exposed?

Once you have completed the insulation process, you may wonder whether you can leave it exposed or if it’s necessary to cover it. A simple rule of thumb is, if the room is for storage purposes only, there is no need to cover the insulation.

Otherwise, it is better and much safer to cover it. Uncovered insulation can pose a fire hazard. It can also pose health problems if people are exposed to the insulation materials for a long time. 


Shiplap is an attractive wall finishing, but it’s important that you take all necessary steps to ensure it’s sufficiently insulated and weatherproof (if using outdoors). This will help in both the winter to keep you warm and the summer to keep things cool.

If you’re interested in insulation, you may also want to read about how to insulate laminate flooring.