It looks web apps lock access to their root slug, just like they do in BC, making it impossible to create a page at that slug. For example, if your web app is rooted at /solutions, a web app item can be at /solutions/cool_service, but you can't use /solutions for anything, even outside of the web app. 

This is an example of what the current detail layout looks like:

---
layout: templates/1
slug: solutions
---
{% include 'modules/siteglide_system/constants' -%}
{%- assign _slug = context.location.pathname | replace: '/solutions/', '' -%}
{%- if _slug == blank -%}
	{%- include '404' -%}
{%- else -%}
	{% include 'webapp', id: '38429', type: 'detail', slug: _slug, layout: 'default' -%}
{%- endif -%}

And this is what could solve it:

---
layout: templates/1
slug: solutions/:item_slug
---
{% include 'modules/siteglide_system/constants' -%}
{% if context.params.item_slug %}
	{% include 'webapp', id: '38429', type: 'detail', slug: _slug, layout: 'default' -%}
{%- else -%}
	{%- include '404' -%}
{% endif %}

(the key difference is the slug line. I don't know why I included that whole segment of code) 

I wouldn't be surprised if this has already been thought through. There may be a very good reason it isn't implemented, or maybe it already is, and I'm just a dope! ;)