Product Profile: Davit Systems

Davit arms are commonly used to rig over non-structural parapets, decorative cornices, and glass balcony guardrails. These arms act as the primary suspension points usually for swingstages, but are also used for supporting single man cages and bosun's chairs. Comprised of a mast (the vertical) and boom (the horizontal), davit arms are secured to structure using bases. These bases vary to suit the roof or wall construction.

The main distinction in davit systems is whether or not the system is designed to be ground rigged or roof rigged. In a ground rigged scenario, each successive "drop" is done by picking up the platform from ground level, raising it to roof level, then back to the ground level. At ground level the platform is then moved to the next "drop" location.

In a roof rigged scenario, the mast on the davit arm is tall enough to allow it to pick the platform up from ground level, and hoist it onto the roof. The stage is then relocated on the roof level to align with each "drop" location. Please find below an example of roof rigging a stage.

 

Davit arms are typically portable and are relocated to new bases for every drop. They can be broken down into segments for ease of carrying. Mast and boom size vary depending on building requirements. At times, arms that are very large or are required in difficult to access areas, are recommended or necessary to be permanently left in place for facade access. In the below picture, the davits could not be practically moved onto the catwalk, as such the arms there are permanent. Also referred to as, "dedicated arms".

 

 

 

Michael Gray

Marketing and Sales Support
Ontario and Eastern Canada

Pro-Bel Enterprises Ltd

e: mikegray@pro-bel.ca

t: @Pro_Bel

w: www.pro-belgroup.com

 

Not Just Roof Anchors

I don't plug Pro-Bel Enterprises Ltd very often in my blog postings. In fact, I think this may be the first time. I try to post blog articles that are industry specific only and have no bearing on any individual company. However, with this particular blog posting it is unavoidable. I digress.

Pro-Bel Enterprises Ltd is associated with being a provider of window washing, suspended maintenance, and fall protection system products and services. However, there are many products we offer that people are not aware of.

S-5 Clamps / Snowguard Systems

Pro-Bel is an authorized distributor for S-5 (http://www.s-5.com/distributors/Index.cfm?DistCat=6). S-5 is a great product that allows securement of clamps to a standing seam metal roof without penetrating the decking. A common use for these clamps is to secure snowguards.

Guardrail Systems

We can design, manufacture and install permanent or counterweighted guardrail systems.

Breakaway Anchors

Complete with its own internal shock absorber, the breakaway or collapsable roof anchor can be installed right into the roof deck without being secured to the supporting structure underneath.

Hoisting Arm

Much like a davit arm, Pro-Bel can manufacture hoisting arms which are portable and secured on site to permanently installed bases.

Residential Roof Anchor

Residential roof anchors are used on sloped shingled roofs. They can be nailed or screwed directly into the wood truss roof support structure and be used as tie off points for roofers. These are becoming mandatory for roofers in the United States in June, 2011.

Best,

Michael Gray
Marketing and Sales Support
Ontario and Eastern Canada
Pro-Bel Enterprise Ltd
e: mikegray@pro-bel.ca
t: @Pro_Bel
w: http://www.pro-belgroup.com/

Working With Concrete

In the roof anchor business, it doesn't matter if its retrofit or new construction. Reinforced concrete is the best of the best when it comes to a structure to work with. It's more cost effective, doesn't typically require localized reinforcing or access to the underside of the structure. It also has a host of other benefits as well such as improved insulation and sound barrier qualities.

The best part in new construction is that we don't have to send anybody to the site for installation which saves everybody time and money. We simply send the anchor to the site with our shop drawings and the anchors are cast in place. There are three types of cast in anchors: single stud, four stud, and fully embedded.

Single stud are the most difficult to physically place for casting in as they only have one bolt from which to balance the anchor.

Four stud are much easier to cast in. As you can imagine they have four studs or bolts from which to vertically support the anchor. These extra three studs are required by engineering for taller anchors.

 And finally we come to fully embedded. This is my personal favorite for two reasons: one its very east to stand up for casting, two, it is more cost effective than both the single and four stud anchors.

In the unfortunate event that a pour is missed by the roof anchor manufacturer and the anchor have to be retrofitted, its not as bad as you think. We simply have use an adhesive anchor and glue, or epoxy the roof anchors into place.

There is also an option of using a bolt through style anchor in the chance happening that is pour is missed to retrofit the anchor it but I would not recommend it. The bolt through style anchor requires access to the underside of the structure to complete installation and it also requires leaving a plate exposed.

For its strength and forgiving nature, concrete is definitely the structure of choice for roof anchor manufacturers.

Best,


Michael Gray
Marketing and Sales Support
Ontario and Eastern Canada
Pro-Bel Enterprises Ltd
e: mikegray@pro-bel.ca
t: @Pro_Bel
w: www.pro-belgroup.com

Late Contract Awards and Shop Drawings

Far too often contracts are awarded at the eleventh hour. Window washing, suspended maintenance and fall protection systems are no different than any other trade in the sense that it requires time to book the job in, review contracts, complete shop drawings, get drawings stamped, get approval from the client, manufacture equipment, schedule installation etc... The understanding can at times seem to be that since the product is required only on the roof, it can be left to the last minute on the project.

At the end of the day, for whatever reason the contract has been issued late in the game. Now, one of the most important factors in quick turn around time for shop drawings is getting CAD files. If the architect or owner has decided to not release cad files to subtrades, than they and the general contractor have to understand that shop drawings will have to be completely drawn from scratch. This takes time. Every line, detail and dimension must be manually drawn  from whatever hard copies are available. If at all possible, an FTP site with all the CAD's is the ideal. If that is not an option, the roof anchor contractor needs:

• roof plans (both architectural and structural)
• floor plans (typical floor is acceptable if applicable)
• elevations
• building sections / wall sections
• all xrefs to be either included or embedded

At times, there is a charge for CAD drawings. They aren't cheap in these cases. They usually run around $100 a sheet or more. I have personally seen charges as high as $200 per sheet. You have to imagine that on a small margin job there is absolutely no room for a sub contractor absorb these costs. They would rather take longer producing shop drawings from scratch than paying ludicrous fees to meet a tight deadline.

If the roof anchor contractor has the CAD files, producing shop drawings is relatively easy. Point and click where the anchors go, show a few connection details and "drops", put a few notes on the drawing, get it stamped and send it out.

If the situation makes awarding the window washing, suspended maintenance, and fall protection systems at the last minute an absolute necessity, let's give the contractor everything they need to get the job done. With the exception of high security projects, their is no good reason to date that I have heard in my career for withholding, or charging exorbitant amounts for release of CAD drawings to subcontractors.


Best,

Michael Gray
Marketing and Sales Support
Ontario and Eastern Canada
Pro-Bel Enterprises Ltd
e: mikegray@pro-bel.ca
t: @Pro_Bel
w: www.pro-belgroup.com