Porch Insulation: What, Why, How

When planning your home, porch insulation may not be the first thing on your mind. However, it should be somewhere on your radar for a few reasons. Beyond the obvious functionality, it can also add value to your home and improve its heat retention. This is all well and good – but how exactly should you go about insulating the porch? That’s what we’re here to discuss today, so buckle in; this is gonna be a fun one.

Porch insulation improves heat retention during the winter and keeps it cool in summer. It also adds value to the home, improves its heat retention, and is generally a good idea.

There are a lot of things that add to that statement, so let’s dive right in – there’s a lot to cover today.

Porch Insulation Basics

Let’s start with what one might think is an obvious statement. If your porch isn’t enclosed, don’t worry about insulating it. Until there are walls to help trap heat, the insulation will be nearly useless in an open porch.

However, if you’ve got an enclosed porch, there’s a lot that you can do to make it more welcoming, both in the summer and winter. I think the first thing we should look at would realistically be insulation. We recently talked about loft insulation types and a lot of that information will carry over here, so I highly recommend that you check that article out. I’ll recap a few of the basic points, but most of the fine details will be in that article. Now – how should you choose insulation?

Picking the Right Insulation For the Job

First things first – most of the insulation listed here should be installed by a professional. If you live in an area that requires strong insulation (high R-value), then the ones you can do yourself are really not going to cut it. Things like fibreglass batts are easy to install and affordable, yeah – but you get what you pay for.

Spray Foam

This is likely your best bet if you’re in a humid, wet, or extremely cold environment. While it’s best left to the professionals to install, there’s a good reason. When installed properly, closed-cell foam insulation boasts a massive R-value of R-6.5. That’s higher than most comparable insulations, though it’s more expensive because of this.

If also acts as an air barrier, making it an ideal choice when closing in a porch. It will be one of the best options out there to keep your porch comfortable and wind-free in just about any weather.


Generally installed with the help of a professional, polystyrene insulation is a great choice for most insulation projects. It boasts a relatively high R-value at R-5 per 2.5 cm (1 inch), and is very effective when measured by weight.

Just like spray foam, polystyrene insulation’s biggest downfall is that it’s expensive when purchasing enough to insulate a large area (like your porch or loft).

Rigid Foam Insulation

This is one that wasn’t covered in the above article, so let’s talk a bit about it. They’re, well, rigid boards of foam that act as insulation. They come in three types – POLYISO, XPS, and EPS.

Polyiso insulation has the highest R-value and, consequently, the highest cost. If foil-faced, polyiso boasts an R-value of roughly R-6.5 per 2.5 cm, which puts it on par with spray foam. This makes it one of the best choices if cost isn’t an issue – especially if you live in a particularly cold environment. Its one major downside is that over time, it off-gasses the gasses present in the foam, losing its effectiveness over time.

This means you will need to replace it over time, so keep that in mind.


While I would never actively choose cellulose insulation if I could afford one of the above, sometimes needs must be met with the budget you have. Not only is cellulose easy to install yourself, but it performs pretty well. It won’t do as well in extremely cold environments as polystyrene or spray foam, but it will work great for moisture and frost resistance.

It also has boric acid mixed in to deter insects, meaning that your porch will likely be free of any infestations – so that’s a nice bonus. If you can get ahold of the equipment to wet-spray it in, you’ll also get better performance and it will be a bit easier to install – though it’ll cost you.

What Will DIY Insulation Require?

Okay, first things first – I highly recommend hiring a professional to lay your insulation. This goes doubly if you’ve never installed it before. Not only is insulation not really a fun thing to put in, but it’s gruelling and can often require specialised equipment to install properly. And worse, you may not realise you need specialised equipment. I’ve seen several friends just try to do it themselves, and they ended up needing to hire someone to fix their mistake. That doubled their costs nearly overnight and was, at the very least, quite embarrassing.

But if you’re dead-set on installing this insulation yourself, here’s what you’ll need:

  • Eye protection (it should form a seal around your eyes)
    • A lot of insulation (especially fibreglass, which we didn’t talk about here) kicks up particles during insulation. These can be bad for your eyes and can potentially be carcinogenic if inhaled. Do not skip any of the safety equipment here, and don’t skimp on it, either.
  • Respirator – we’re not talking a disposable cloth mask like you used during the pandemic. No, you need a respirator, with an actual filter. (Example pictured above)
  • Good work gloves
  • A hat or cap (to keep stray insulation out of your hair)

Tips & Tricks for Porch Insulation

While the actual process will vary depending on the type of insulation you opt for, there are a few good basics to keep in mind.

  • Apply a vapor barrier before laying any insulation. This will add an extra layer of protection against moisture.
  • If you’re using insulation that comes in boards or sheets, opting for spray foam insulation alongside it will massively improve your insulation’s performance. You’ll be able to fill in gaps that the boards miss, and you porch will be even comfier come winter.
    • Any gap in insulation will provide a place for moisture, drafts, and outside weather to make its way in.
  • If laying polyiso rigid foam boards, place the silver side towards your ceiling and it will perform much better.

Final Thoughts

Okay – if you’re thinking about insulating your porch, there’s a lot to know. The most important thing to take into account is your environment. Where you live will greatly affect what the best choice in insulation is. A more temperate climate can get away with using lower R-value insulation (that’s consequently cheaper) than an extremely humid or cold one could. In addition, who installs your insulation will likely make a big difference.

If you do it yourself, it’s going to get done for much cheaper. However, there’s a chance that you could install it improperly or just miss spots, meaning you’ll eventually have to redo the job. Whether that means you have to take another weekend to reinstall insulation or hire a pro to do it, that’s wasted time and money. For that reason, I highly recommend that you hire a professional to install your insulation.

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About the Author Harry Thompson

Involved in home renovations throughout his life, Harry is an expert in everything to do with home and garden DIY. In his spare time, he enjoys cooking and tending to his garden.