Using wire for infill vs. cable in horizontal deck railing

[Allen Ingling]

This question has been brought up in past threads, specifically for a recommendation for the sizing of wire to be used. Most of the replies have been negative to the idea, even dismissive. It is apparent that most inspectors are still not at ease with horizontal infill but it is becoming very popular, especially in high end construction, both outside and inside for decks, lofts, and stairs. We cannot ignore this and should strive to provide good information to our clients where possible. If an inspector is not comfortable with this technology then it is appropriate to refer clients to PE's or other sources. That said, this is not rocket science and a little thought can be applied and some general information provided. Stranded, stainless steel (occasionally galvanized), cable is the general material used, most commonly 3/16 inch diameter. As small as 1/8 inch diameter is used but the breaking strength (as low as 500 lbs.) is in the same order of magnitude as the recommended installation tension (300 lbs.) and should probably not be recommended, also the stiffness of 1/8 inch cable might be insufficient to pass the 4/50 test (4" rigid ball, 50 lbs force). The use of single wire vs. cable should be acceptable and not dismissed out of hand. For one consideration, single wire is stiffer than cable. As to tensile strength, 8 ga. stainless (302, 304,316) wire of medium hardness has about one ton breaking strength and should be plenty strong enough and about the minimum acceptable size. If installed properly, with 300 lbs. or more tension it should pass the ball test. If the highest quality (spring steel) stainless wire is used it has about twice the breaking strength of medium wire and is even stiffer. All horizontal cabling should be installed at the commonly recommended spacing of no more than 3 inches horizontally with vertical gauges in the 3-4 foot range to maintain the spacing.

[Jerry Peck]

This question has been brought up in past threads, specifically for a recommendation for the sizing of wire to be used. Most of the replies have been negative to the idea, even dismissive. It is apparent that most inspectors are still not at ease with horizontal infill but it is becoming very popular, especially in high end construction, both outside and inside for decks, lofts, and stairs. We cannot ignore this and should strive to provide good information to our clients where possible. If an inspector is not comfortable with this technology then it is appropriate to refer clients to PE's or other sources. That said, this is not rocket science and a little thought can be applied and some general information provided. Stranded, stainless steel (occasionally galvanized), cable is the general material used, most commonly 3/16 inch diameter. As small as 1/8 inch diameter is used but the breaking strength (as low as 500 lbs.) is in the same order of magnitude as the recommended installation tension (300 lbs.) and should probably not be recommended, also the stiffness of 1/8 inch cable might be insufficient to pass the 4/50 test (4" rigid ball, 50 lbs force). The use of single wire vs. cable should be acceptable and not dismissed out of hand. For one consideration, single wire is stiffer than cable. As to tensile strength, 8 ga. stainless (302, 304,316) wire of medium hardness has about one ton breaking strength and should be plenty strong enough and about the minimum acceptable size. If installed properly, with 300 lbs. or more tension it should pass the ball test. If the highest quality (spring steel) stainless wire is used it has about twice the breaking strength of medium wire and is even stiffer. All horizontal cabling should be installed at the commonly recommended spacing of no more than 3 inches horizontally with vertical gauges in the 3-4 foot range to maintain the spacing.

Wire in-fill is not dismissed out of hand, it is dismissed (put down) with considerable wonderment and amazement at the architects, designers, and the clients themselves for two reasons: a) if the wire is not properly tightened then the space easily exceeds the allowable 'shall not allow a 4 inch sphere to pass' (and thus does not meet code as code requires the in-fill to not allow a 4 inch sphere to pass through); b) if the wire is actually properly tightened then the space will reject the 4 inch sphere and not allow it to pass through, however, when the cables are tightened that tight the wire/cable in-fill now creates a ladder for the younguns to climb up and over the guard (code does not address this stupidity).

It is not the wire/cable which is the problem when properly tightened, it is the running of the wire/cable horizontally which creates the problem - take that same wire and run it vertically and properly tightened so as to not allow a 4 inch sphere to pass and then there is no problem.

Run the wire/cable horizontally and one might as well lay a ladder next to the guard so the younguns can climb up and over the guard ... wait ... with properly tightened horizontally run wire/cable the ladder is already there ...

but that is stupidity at a higher level than many are able to achieve in a lifetime ... mind you, not stupidity at its highest level, we see higher levels of stupidity all too frequently, but it is usually not done in the name of 'style' or 'I like the way it looks that way'. You like looking down the barrel of a loaded gun? With the safety 'off'? The 'safety' is not even present on those horizontal wire/cable guards, someone left that on the breakfast table next to their brains when they decided to go with an in-fill panel made of horizontal wire/cable.

But, seriously, if you want I can tell you how I really feel about those guards with horizontal wires/cables ...

[Bruce Grant]

This question has been brought up in past threads, specifically for a recommendation for the sizing of wire to be used. Most of the replies have been negative to the idea, even dismissive. It is apparent that most inspectors are still not at ease with horizontal infill but it is becoming very popular, especially in high end construction, both outside and inside for decks, lofts, and stairs. We cannot ignore this and should strive to provide good information to our clients where possible. If an inspector is not comfortable with this technology then it is appropriate to refer clients to PE's or other sources. That said, this is not rocket science and a little thought can be applied and some general information provided. Stranded, stainless steel (occasionally galvanized), cable is the general material used, most commonly 3/16 inch diameter. As small as 1/8 inch diameter is used but the breaking strength (as low as 500 lbs.) is in the same order of magnitude as the recommended installation tension (300 lbs.) and should probably not be recommended, also the stiffness of 1/8 inch cable might be insufficient to pass the 4/50 test (4" rigid ball, 50 lbs force). The use of single wire vs. cable should be acceptable and not dismissed out of hand. For one consideration, single wire is stiffer than cable. As to tensile strength, 8 ga. stainless (302, 304,316) wire of medium hardness has about one ton breaking strength and should be plenty strong enough and about the minimum acceptable size. If installed properly, with 300 lbs. or more tension it should pass the ball test. If the highest quality (spring steel) stainless wire is used it has about twice the breaking strength of medium wire and is even stiffer. All horizontal cabling should be installed at the commonly recommended spacing of no more than 3 inches horizontally with vertical gauges in the 3-4 foot range to maintain the spacing.

It is a modern popular look but it comes from the commercial building side of design which follows far differing codes than residences for guards. In Ontario horizontal guards are allowed in commercial application both for stairs and edge guards Specifications are supplied by the consulting architects depending on the material used and the distance desired between uprights. There is a lot more leeway within the commercial building community simply because the local building authority has no responsibility for the design criteria. Once the engineer or architect stamps the design the building dpt is there only to see the work properly installed using the materials spec'd.
In residential work the local building dpt has the responsibility to ensure the work is built to his/her design , the building code. In Ontario that means no wire or bar type fill horizontal guards on edge guards. They will however pass horizontal wire or bar fill type guards for stair guards according to my local building code enforcement official.
Apparently the guard fill running on an angle of the stairs does not constitute a horizontal surface was the explanation I got.
Bruce Grant
Done Right Home Inspections

[Jerry Peck]

Once the engineer or architect stamps the design the building dpt is there only to see the work properly installed using the materials spec'd.

May be that way up there, but down here the building department reviews the documents to architect or engineer draws up for code compliance - if the documents are not compliant with the requirements of the code then the documents are not approved and returned with comments citing what is not in compliance. The architect or engineer then does a revision and resubmits the documents. IF the architect or engineer is not on the ball or is trying to get away with something (i.e., does not address all the comments from the building department), then the documents will not be approved and will be returned with comments stating what is not in compliance.

One of the project I am inspecting is so far from the requirements of the code, yet was signed off and approved by the AHJ, whoever signed off and approved those document should be drawn, quartered, and fed to the architect as good BBQ where 'the secret's in the sauce' regarding the superb BBQ.

[Bruce Grant]

May be that way up there, but down here the building department reviews the documents to architect or engineer draws up for code compliance - if the documents are not compliant with the requirements of the code then the documents are not approved and returned with comments citing what is not in compliance. The architect or engineer then does a revision and resubmits the documents. IF the architect or engineer is not on the ball or is trying to get away with something (i.e., does not address all the comments from the building department), then the documents will not be approved and will be returned with comments stating what is not in compliance.

One of the project I am inspecting is so far from the requirements of the code, yet was signed off and approved by the AHJ, whoever signed off and approved those document should be drawn, quartered, and fed to the architect as good BBQ where 'the secret's in the sauce' regarding the superb BBQ.

Jerry I guess the difference may lie in the professional and education status as both architect and engineers require university degrees both 4 year with major in the respective field in addition the architect requires an apprenticeship and both professions require a license and have organizations that can impose penalties as well as both are required to have extensive insurance. On the other hand many of the building inspectors I have encountered were by no mean stupid but twenty years ago might have finished high school . Most though were trades trained converting to less strenuous work. Today many local building inspectors take what you would recognize as community college credit courses and or come up through the municipal staff with on job training and coursework. None are required to be licensed its not considered a profession just a job and as such they do not carry insurance the municipal body holds that and is responsible for their decisions and conduct as well as for the municipality itself. None of them in short are considered educated or knowledgeable enough for a municipality to override the judgement of the licensed professional (when it comes to building specifications) they trust that the professional body and educational system prevent said professionals from skimping or skirting proper building codes and practices.. Here except in the largest cities I doubt that there are even many able to read and evaluate much more than the most basic plan sets. On the other hand there is just now a professional engineer headed to trial for the mall collapse in Elliot Lake 2 years age . He did the building inspection that year and missed some very important information . It collapsed killing two and he has been charge with two counts of manslaughter. He will take the fall do eight years or so as he is an older man now and he has already lost his license. Hell of a way to end a career.

[Jerry Peck]

Jerry I guess the difference may lie in the professional and education status as both architect and engineers require university degrees both 4 year with major in the respective field in addition the architect requires an apprenticeship and both professions require a license and have organizations that can impose penalties as well as both are required to have extensive insurance.

Having all that edumucation means they were taught a lot of stuff, were able to pass the test, and (at least in Florida) do a two apprenticeship under another architect or engineer.

What that does not mean is that they have the ability to take what was taught to them and put it into a plan for a successful structure. I too have seen many mistakes by architects and engineers which common sense catches and says 'Whoa, did you mean to do that intentionally, or was that a mistake?'

That is the reason they have the licensing boards and the reason the licensing boards are kept so busy - because all that education does not mean a good or smart architect or engineer - they are human, just like the rest of us.

[Bruce Grant]

Having all that edumucation means they were taught a lot of stuff, were able to pass the test, and (at least in Florida) do a two apprenticeship under another architect or engineer.

What that does not mean is that they have the ability to take what was taught to them and put it into a plan for a successful structure. I too have seen many mistakes by architects and engineers which common sense catches and says 'Whoa, did you mean to do that intentionally, or was that a mistake?'

That is the reason they have the licensing boards and the reason the licensing boards are kept so busy - because all that education does not mean a good or smart architect or engineer - they are human, just like the rest of us.

You are sure right there Jerry, we have boards and courts to right mistakes they may make but one of my favourite stories I have related to my kids several times when we discussed responsibility I'll relate it here.
Years ago I read an article in Readers Digest about architect who designed a nine story residential apartment building in the heart of the then rebuilding city of Moscow under Khrushchev's rebuilding program of the late 60's. The architect proudly designed and submitted his building design and it went through the committees for approvals etc. He then oversaw the building process. When finished he housing committee discovered he had failed to include elevators in the design. Rather than sue him or take away his license they assigned him and all his family the ninth floor apartments.

[Michael Thomas]

"Professional certification" does not guarantee "professional competence" or even "common sense".

In the construction consulting end of my business I continually encounter examples of what I call "When CAD goes bad": architects specify construction details which are extremely difficult to build in a durably waterproof manner, and then leave it to the builder to implement the design, sometimes with very expensive consequences.