What’s the safest way to share drawings between architect, builder and subcontractors?

The safest way is to keep the drawings in one shared project area and give each firm controlled access to it, rather than emailing copies around. Everyone opens the current revision from the same place, each firm sees only what it needs, and access ends when the job does.

On any build, drawings travel. The architect issues them, the main contractor shares them, the engineer revises them, and each subcontractor needs the latest version for their part of the job. On a busy project that can mean dozens of people across half a dozen firms, all working from the same set of drawings. In a lot of firms, that still happens by email attachment. It works until it does not.

What goes wrong with email attachments?

• Nobody knows which version is current. Revision C goes out, then revision D, and someone on site is still working from the copy they saved last month.
• Copies end up everywhere. Every attachment is another copy in someone’s inbox, on their laptop and in their downloads folder. You cannot take any of them back.
• Files are too big. Drawing packages hit email size limits, so people turn to whatever free file-transfer site they find, with no control over who else can open the link.
• Fake “shared drawing” emails look normal. If your team is used to clicking links to drawings from people they do not know well, a fraudster’s link to a “revised drawing” does not stand out. Our post on how payment fraud hits a building firm shows where that can lead.

What does a safer setup look like?

Keep project drawings in one shared location and give each firm access to it. The principles matter more than the particular tool:

• One source of truth. The current drawings live in one place, so everyone sees the same revision.
• Access by firm and by person. Each subcontractor sees the folders for their trade, not the whole project and certainly not your other projects.
• Read-only where possible. Most people need to view and print drawings, not change them.
• Links that expire. When you share with someone outside the firm, set an end date. Access should not outlast the job.
• A record of who opened what. If there is a dispute about which revision someone worked from, you can check.
• Access removed at the end of the job. When a subcontractor finishes, their access goes. When the project closes, all external access goes.

If you use Microsoft 365, SharePoint already supports most of this. According to Microsoft’s sharing settings, an administrator can require links shared with anyone outside the firm to expire within a set number of days, allow sharing only with guests who are already in the directory, or limit sharing to particular partner organisations.

Does a small firm need a formal BIM process for this?

Not to get most of the benefit. Architects and engineers working to the ISO 19650 series, which sits within what is now the IMI Framework (formerly the UK BIM Framework), manage project information on the same principle: exchanging, recording, versioning and organising it for everyone involved. A smaller firm can apply the principle without the full process. A well-organised shared project area with sensible permissions does most of the job.

Who should host the shared area, the architect or the builder?

Both ends of the chain have something to protect. The architect’s drawings are their intellectual property and their professional liability. The builder’s project area holds pricing, programme and subcontractor information alongside the drawings. Neither wants everything visible to everyone.

That is why access should be set by role, and why it is worth agreeing at the start of a project who hosts the shared area, who controls access, and what happens to it when the job is finished. If the client or main contractor specifies how project information must be managed, follow their requirements.

What about shared models, not just drawings?

The same rule applies when the project works from shared 3D models rather than PDFs. Keep one controlled place for the current model, give each firm access to what it needs, and make sure superseded versions are clearly marked so nobody builds from an old one.

How do you stop people falling back to email?

People fall back to email attachments because they are quick. If the shared area is slow, confusing or needs a separate login for every project, they will keep doing it. A good setup is one where opening the current drawing on a phone on site is quicker than finding last week’s attachment. Pair that with a short reminder to staff to be wary of unexpected links to drawings.

Where does this fit with managed IT?

For INNOSEC clients, how files are stored and shared is part of managed IT. Microsoft 365 is included, and looking after it means bringing structure to permissions, document storage, external sharing and ownership, so a shared project area is set up properly and external access comes off when a job ends.

We work with architects and engineers as well as builders, so we see both ends of this. See IT support for architects and engineers and IT support for construction companies.

Once a project is complete, the shared files become your record of what was issued. Our guide to what to do with drawings and models when a project ends covers archiving them.

Frequently asked questions

Can subcontractors without Microsoft 365 still use a shared area?

Usually, yes. Depending on how your administrator has set up sharing, people outside the firm can be invited as guests and verify themselves with a code sent to their email, as Microsoft’s sharing settings describe.

How long should external access last?

Only as long as the job, or the part of it that firm is working on. Setting an end date when you share, and reviewing access at project close, keeps it that way.

Is a free file-transfer site fine for one large file?

It moves the file, but you lose control of who else can open the link and for how long. If large files are the reason people use them, a shared project area with expiring links solves the same problem.