Roof Support Blocks on Flat Roof


Flat Roof Here - Densboard, Tri Ply Base, 2 Sheets of APP 160.

My HVAC units are installed on the parapet.
I am considering adding roof support blocks/strut for some slight added support .

For all you pros who see rooftops all day, over the long term, when the weather is hot and the roof sheets get ~soft~, does water pool around these areas due to possible ~isolted weight depressions~ ?


yes. The Dens should help out but the APP will get soft in hot weather and might cause the support to sink. Use something to spread the weight.


Indeed on the APP. Even noticed in bright sunlight - mild low 60’s that it has some softness to it.

The mechanicals are supported vis-via brackets on the parapet.
I was simply looking to add the roof support block/strut as a secondary means of support underneath the bracket. My concern was long term depressions where the roof block meet’s the membrane. Then again, I SEE a bajillion commercial roofs and these roof blocks seem pretty standard - as well as steel I beams…

Anyhow, I don’t know how FLAT a brand new flat roof should be. Not pitch, but surface wise.
It was nice and FLAT when they put the densdeck/tri ply base.
Both layers of APP, as they laid it, they were walking all over the HOT membrane. Subsequently, the finished product has small minor indentations all over the place.
I was sorta expecting/thinking since it was a full tearoff/rebuild, the finished product would be ///FLAT.


heading over to the supply house to buy some kindorf, fittings and roof support blocks.

I was on the roof the other day. It was pretty hard…

Which got me thinking. Maybe there is a slight longer CURE time with alum roof coating and what I was feeling minute sponginess, was the topcoat ?

I doubt the tar under the roof sheets get soft, but the membrane might.
Should I be concerned about me causing pooling spots/slight depressions where the roof block is. See post #3 - my brand new tearoff top bidder roofer, is not exactly a --flat flat roof-- but more with some minor indentions all over. Hell, on the 1st layer of APP, there was some areas where it was SO BAD, as there was tread indentions 1/8-3/16 dee–from the roofers boots. The 2nd layer, they were careful about this after I pointed it out…

The alum coating does some minor masking/filling of these depressions, but still, technically, the roof is not flat like I expected.