Do I need to seal H4 timber outdoor stairs?

PujDD

Hi all,

I've heard mixed opinions on whether outdoor timber stairs made of H4 treated pine need sealing.

We've recently bought our first home which has some outdoor stairs. These stairs were almost slimy slick when wet due to grime build up on the stain, so we gurneyed them down to prevent slipping injuries particularly in the rain. 

There is some cracking now starting to appear in the stairs. Should we be resealing them? When's the best time to do this and what type of product should we use? 

Pictures for reference  

 stairs midway through gurneying

EricL

Hello @PujDD 

Welcome to the Bunnings Workshop community. It's wonderful to have you join us, and thank you for sharing your question about painting your timber steps.

H4 timber is chemically treated to withstand insect and termite attack, it's also rated for outdoor use and direct contact with the soil. Technically speaking you don't need to seal it. However, its top surface or outer layer is subject to the weathering process. As the seasons pass the timbers outer layer is subject to battering rain and intense sunshine. Eventually the timbers outer surface will get damaged and wear away.

In order to add an extra layer of protection, you have the option of sealing or painting the timber surface. I suggest washing it with Cabot's 1L Deck Clean, this will wash away dirt, oils, grease and other contaminants. It will also restore and rejuvenate the timber surface. Once the surface is clean and dry, I propose looking at Cabots 1L Aquadeck Natural Exterior Decking Oil as a possible sealer for your steps.

There are other sealers with stains in them, I suggest visiting your local store if you wish to see the other finishes. My best advice is to test a small section of the bottom of the steps with the oil of your choice. If you are happy with the finish, you can then commit the rest of the steps.

If you will be having several days of good sunny weather and reasonable temperature, it's possible to apply the sealer. However, days with rain or heavy moisture and cold temperatures are to be avoided.

Please make sure to wear personal protection such as gloves, goggles and a mask when cleaning and painting your timber steps. Please do not sand the surface of the steps as the timber itself is treated with chemicals.

Here is a handy step-by-step guide: How to stain a deck (the techniques used are applicable to your steps)

If you need further assistance, please let us know.

Eric