I would like to fasten (2) 30 inch 2x3's to an exterior concrete block wall along with a 2x3 screwed to the front door header to form a triangle over the door to support a wood canopy. I would prefer not to attempt to nail or screw into the concrete block. Does anyone having any experience using Liquid nails or other construction adhesive think this will hold? The canopy should weigh 30 to 40 Lbs. If yes, does the paint on the wall need to be removed first?
Thanks, Jim

Liquid Nails will hold just about anything, once dry. However it may take as long a 6 months to completely dry when trapped between two surfaces. Don't be afraid to try to nail into blocks. Just get some 2 1/2' cut nails (those are the ones with flat sides and no point) and a big hammer. Drive three or four nails almost through the 2x3, don't get too close to the ends. Turn the flat side of the nails pararall to the grain of the wood. Put the Liquid Nails on the 2x3, put it in place and drive the nails flush. Hit the nails hard, don't tap them, the fewer blows you need to drive them home the better. The Liquid Nails will hold the 2x3 to the wall and the cut nails will take the shear or downward force. While the cut nails will take the shear force they will pull out of the concrete fairly easily. They only work because they are wedge shaped. If the blocks are concrete it won't be hard, if the blocks are cinder blocks it will be real easy.
Wait several days or a week for the Liquid Nails to dry.

Liquid Nails makes over 40 different products ands not all are suitable for outside work attaching to block. Try https://www.askmehelpdesk.com/constr...80112-new.html , it should meet your needs but I'd still back it up with some nails. Harolds cut nails should do the trick. I use a Remington 22 cal. nail gun. Most of the LN product dry to full strength in about a week.

Thanks guys! Need encouragement to get over fear of putting holes in the front of my house. As far as the extra support, are nails better than masonry screws? I'm sure the cut nails would go directly into the block but are there anchored screws that could go into the mortar joints?
Thanks again,
Jim

Hey Jim, there are screws for your application, just look in the aisle with all of the screws and look for long blue screws that are labeled for masonary, they are called Tapcons. You are better off to go through the block itself and avoid the mortar lines. Commonly asked questions about Tapcon&reg Concrete Screw Anchors